Variant Attributes Gryed Out Field

Hi All,

The Transportation Report VT12 dose not have the Field OvSts.ShCostCa (FBGST) in the selection criteria. If go to the variant maintanance screen i can see the field but it is greyed out. I cannot un hide this field.

I have searched this on the fourm but could not find something which made sense to me. have followed this link but the field is still greyd out in SE38 Variants Change.