Graphical Mapping Issue

Hi,

I have a scenario where I am getting data from Idoc and sending to SAP R/3 via RFC call through XI 3.0. I have configured mapping in Graphical Mapping (GM) between Idoc and RFC but having problem where if one of the Field (ITEM_AMOUNT) is zero value in RFC side then I do not want to create the line item to send to SAP R/3.

Can somebody please suggest how I can achieve this or any suggestion in terms of coding how I should go about it.

TIA

Ranjan