Hi John;
My guess is that the FindWindow is failing to get the other application EXE's Window handle properly.
BTW: You should be using either FindWindowW or FindWindowExW MS-Windows API's in PB 10 & higher as PB is now Unicode.
FUNCTION uLong FindWindow ( ref String classname, ref string windowname ) Library "USER32.DLL" ALIAS FOR "FindWindowW"
HTH
Regards ... Chris