SendMessage API fails after converting the app into PB12.5

Hi
We had the following API declaration that worked for years in PB9:

FUNCTION ulong TabCtrl_HitTest (ulong hwnd,uInt  wMsg,ulong wParam, ref st_hittest lParam) LIBRARY "user32.dll" ALIAS FOR "SendMessageA"
FUNCTION ulong TabCtrl_GetItem (ulong hwnd,uInt  wMsg,ulong wParam, ref st_tc_item lParam) LIBRARY "user32.dll" ALIAS FOR "SendMessageA"

Now in PB12.5 migrated code it autmotically added ";Ansi" clause to those declarations.

Call of TabCtrl_HitTest constantly returns -1 instead of the number of the hovering tab page.

Any help will be greatly appreciated.

Thank you
Michael