这样的XML如何会有错，实在不明白啊求教

<LinearLayout     xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"     android:orientation="vertical"    >    <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >                <TextView            android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:textSize="@string/text_size"       android:text="@string/tv_lactate_date_text"       >        </TextView>               <EditText             android:id="@+id/et_lactate_date"            android:layout_width="0dp"       android:layout_height="wrap_content"       android:textSize="@string/text_size"       android:layout_weight="1"       android:inputType="date"       android:enabled="false"       />    </LinearLayout>        <LinearLayout        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal" >               <TextView        android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:textSize="@string/text_size"       android:text="时间"            />                <EditText             android:id="@+id/et_lactate_time"            android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:textSize="@string/text_size"       android:layout_weight="1"       android:inputType="time"       />                <Button             android:id="@+id/bt_get_now"       android:layout_width="wrap_content"       android:layout_height="wrap_content"       android:textSize="@string/text_size"       android:text="当前"            />           </LinearLayout>    </LinearLayout>

package com.example.babygrowingup;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.view.MenuItem;import android.support.v4.app.NavUtils;public class MainActivity extends Activity {    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.activity_main, menu);        return true;    }    }

07-17 18:19:48.221: W/dalvikvm(1198): threadid=1: thread exiting with uncaught exception (group=0x40a13300)07-17 18:19:48.251: E/AndroidRuntime(1198): FATAL EXCEPTION: main07-17 18:19:48.251: E/AndroidRuntime(1198): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.babygrowingup/com.example.babygrowingup.MainActivity}: android.view.InflateException: Binary XML file line #12: Error inflating class <unknown>07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.ActivityThread.access$600(ActivityThread.java:130)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.os.Handler.dispatchMessage(Handler.java:99)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.os.Looper.loop(Looper.java:137)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.ActivityThread.main(ActivityThread.java:4745)07-17 18:19:48.251: E/AndroidRuntime(1198):     at java.lang.reflect.Method.invokeNative(Native Method)07-17 18:19:48.251: E/AndroidRuntime(1198):     at java.lang.reflect.Method.invoke(Method.java:511)07-17 18:19:48.251: E/AndroidRuntime(1198):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)07-17 18:19:48.251: E/AndroidRuntime(1198):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)07-17 18:19:48.251: E/AndroidRuntime(1198):     at dalvik.system.NativeStart.main(Native Method)07-17 18:19:48.251: E/AndroidRuntime(1198): Caused by: android.view.InflateException: Binary XML file line #12: Error inflating class <unknown>07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.createView(LayoutInflater.java:613)07-17 18:19:48.251: E/AndroidRuntime(1198):     at com.android.internal.policy.impl.PhoneLayoutInflater.onCreateView(PhoneLayoutInflater.java:56)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.onCreateView(LayoutInflater.java:660)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:685)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:746)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.rInflate(LayoutInflater.java:749)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.inflate(LayoutInflater.java:489)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.inflate(LayoutInflater.java:396)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.inflate(LayoutInflater.java:352)07-17 18:19:48.251: E/AndroidRuntime(1198):     at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:256)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.Activity.setContentView(Activity.java:1867)07-17 18:19:48.251: E/AndroidRuntime(1198):     at com.example.babygrowingup.MainActivity.onCreate(MainActivity.java:14)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.Activity.performCreate(Activity.java:5008)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)07-17 18:19:48.251: E/AndroidRuntime(1198):     ... 11 more07-17 18:19:48.251: E/AndroidRuntime(1198): Caused by: java.lang.reflect.InvocationTargetException07-17 18:19:48.251: E/AndroidRuntime(1198):     at java.lang.reflect.Constructor.constructNative(Native Method)07-17 18:19:48.251: E/AndroidRuntime(1198):     at java.lang.reflect.Constructor.newInstance(Constructor.java:417)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.view.LayoutInflater.createView(LayoutInflater.java:587)07-17 18:19:48.251: E/AndroidRuntime(1198):     ... 25 more07-17 18:19:48.251: E/AndroidRuntime(1198): Caused by: java.lang.UnsupportedOperationException: Can't convert to dimension: type=0x307-17 18:19:48.251: E/AndroidRuntime(1198):     at android.content.res.TypedArray.getDimensionPixelSize(TypedArray.java:463)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.widget.TextView.<init>(TextView.java:780)07-17 18:19:48.251: E/AndroidRuntime(1198):     at android.widget.TextView.<init>(TextView.java:442)07-17 18:19:48.251: E/AndroidRuntime(1198):     ... 28 more