Assign trigger to existing field in a proprietary software

Hi all,

We have a proprietary software that needs custom adjustments once in a while.

Right now we are trying to assign a trigger on a existing field in one of the programs windows (a text-box).

But so far we weren't able to do so, despite numerous tries.

Here is what our code look so far (nothing fancy):

IF wgh-child:NAME="qt-un-fat" THEN DO:
ASSIGN wgh-frame-qt-un-fat = wgh-child.

ASSIGN wgh-frame-qt-un-fat:TRIGGERS:
ON "MOUSE-SELECT-DBLCLICK":U PERSISTENT RUN espUpc\espd4000-u03.p.
END TRIGGERS.

END.

Is there something we are missing here or some other approach we could use?

Thank you.