pb9 调用 api 有关问题

pb9 调用 api 问题
在 Local External Functions 里面定义了如下
Function ulong GetComputerName(ref String ls_Buffer, int nSize) Library "kernel32"

但在一个button 里面调用确出错：
string ls_computer_name
ls_computer_name = space(100)

GetComputerName(ls_computer_name,100)
MessageBox("",ls_computer_name) 

显示：Error calling external function getcomputername at line 23 in clicked event of object cb_3 of w_main
怎么调用啊？

------解决方案--------------------

C/C++ code

string ls_computer_namelong ll_size = 100ls_computer_name = space(ll_size)GetComputerName(ls_computer_name,ll_size)MessageBox("",ls_computer_name)