That error message doesn't match the code you described.
So, did you modify one of them (the code or the error message) when you wrote the post? Or maybe the error is related to some other line of your script.
That error message would mean that your script is trying to do something to the "Title" object in the "Party" vbWindow, but it cannot the "Party" vbWindow. Maybe this window is closed. Maybe it changed its name when you did something else in your application. Maybe it is still open and still called "Party" but one of the other properties you used to identify it in the OR has changed.
"The last 10% of any software project will take 90% of the budgeted time. The first 90% will take the other 90%"