c++ - win32 event calls not working on winxp but working on win7 -

i have c++ service manages com port device (barcode scanner). able read com port fine, , have been working on implementing write functionality send commands scanner request capture image.

i release 32bit build , works fine on windows 7 64 bit. attempted test exact same build on windows xp machine , failed write com port.

i found error setevent(m_writeready) returning true, event isn't being set (atleast wait isn't releasing thread).

m_writeready = createeventw(null, true, false, null); ... const handle handles[7] = {     ...     m_writeready }; ... waitformultipleobjects(sizeof(handles) / sizeof(handle), handles, false, infinite); 

and in thread

setevent(m_writeready); 

what cause waitformultipleobjects not unblock on winxp when works fine on win7/64?