MFC DDE开发中令人迷惑的问题？

在用MFC（ddeml）开发DDE中，遇到一个令人迷惑的问题， ddeml提供的一些命令，在时钟函数里或按钮事件里运行正常，可是在线程里运行就出现如下错误：

"A parameter failed to be validated by the DDEML."

下面是两段代码：

//时钟
void YD::TimerProc(long hwnd,long nIDEvent,long uElapse,long lpTimerFunc)
{
CString strData;
static AAAA=0;
if (AAA.G_connection )
{
strData.Format("T%d", AAAA++);
AAA.G_connection->Advise("aaa",(char *)(const char *)strData);
}
}

//线程
UINT YD::YFDDE(LPVOID pParam)
{
CString strData;
static AAAA=0;

while(1)
{
if (AAA.G_connection )
{
strData.Format("%d", AAAA++);
AAA.G_connection->Advise("aaa",(char *)(const char *)strData);

Sleep(3000);
}

}
return 0;
}

线程和时钟的代码完全一样，可是运行结果不一样，难到ddlml有特殊的限制？这是MSDN说明的理由：

The application used a data handle initialized with a different item name handle than was required by the transaction.

The application used a data handle that was initialized with a different clipboard data format than was required by the transaction.

The application used a client-side conversation handle with a server-side function or vice versa.

The application used a freed data handle or string handle.

More than one instance of the application used the same object.

我也没有弄明白什么意思。

对了，有谁知道侯捷老师的《Windows DDE 动态资料交换》电子版图书在哪里下载？