C++ :: IsDialogMessage - Cursor Not Blinking

I have created a simple WIN32 application. I inserted the function "IsDialogMessage" in the while-loop to make the tabstop key change the textfield. But when I insert the IsDialogMessage-function, the cursor won't blink anymore (it stays static). Is there a way to combine the two (tabstop key = change text field AND blinking cursor)?

Here's my while-loop:

MSG Msg;
while(GetMessage(&Msg, NULL, 0, 0) > 0) {
IsDialogMessage(window,&Msg);
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}

And here I am creating the textfields:

hwnd = CreateWindowExA(NULL, "EDIT", NULL, //no title
WS_CHILD|WS_VISIBLE|WS_BORDER|ES_AUTOHSCROLL|WS_TABSTOP ,
xPos,yPos,width,height,
cWindow->window,(HMENU)502,
(HINSTANCE) GetWindowLong(cWindow->window, GWL_HINSTANCE),NULL);