Expression not working in form

[daddykaggy]

Hello everyone, 

I'm trying to achieve a simple task. I want to have the value that was entered in the row prior appear in a form being filled out for the same table. For some reason my expression -

INDEX(Data[Test], ([_ROWNUMBER] - 1))

is working in the lab test tab and giving me the value I want. But for some reason its not appearing in the form being filled out. Any ideas as to why this is? 

PS - I have this expression entered into the "Initial Value" entry