how to open user defined form while clicking add button in A/P Invoice

Hi Friends,

I am working over A/P invoice screen in this screen i want to open user defined form while clicking add button and i want to load all the information in A/P invoice screen ( details part like itemcode and unit price ect) into my User defined form.

But i am unable to load item details into user defined form. While clicking ADD Button i am opening user defined form.

Any one have solution for this problem please provide solution asap

Thanks & Regards

Naresh.k

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