Trying to use

SendMessage(hwnd_child,WM_SETTEXT,0,(LPARAM)"Test");


It is finding the child fine, I can read text of off it till I'm blue in the face, but I can't seem to get SetText to work.
I've seen posts that say SETTEXT doesn't work between apps in Windows 7, even with elevated priveleges. Is there some other way to set text in a seperate app? It's a vb.net app, that I'm coding.
Sending Settext from a C++ non-visual app.