Object not initialised at changeDesign_BR in PurchTable Form

Hi EveryOne,

               When i try to add a new field to PurchTable form i get the error in ChangeDesign_BR function at element.control(control::Reference_DINumber).visible(false); that object is not initialised. When i remove the new added field everything looks good. Does any one know why a new field addition would not initalise controls in other Tabpages.

This is in Dynamics Ax 2009 SP1

Appreciate your Help..

Shankar