Filter Item lookup on Item category field


I am using Dynamics NAV SP1. My users are using Requisition Worksheet to order Items. There are large number of items in the Item card which belongs to different Item categories. Currently even after users select an Item category, still all the Items of all categories are displayed to them without any filtering.

I want to customize the requisition worksheet so that when an Item category is selected in the work sheet only the relevant items that belong to that category must displayed in the Item No. field look-up.

How can I achieve this?

Version what SP1? 4.0? 5.0? 2009? I guess it doesn’t really matter, but it would be nice to know.

As for filtering, do you have access to the code? If not you should get your NAV partner involved.

It is NAV 5. Yes we do have the developer license. I ned to know exact CAL coding to do this.