Costing relevancy indicator (X) in routing for master recipe

hi All,

I am having a problem that im creating a master recipe and when i assign a resource to the operation the costing relevancy indicator (X) dissappears and this is greyed out. Why is this happening? The control key is PI01 and it is relevant to costing, the WC costing details are also maintained (except activity types). BOM items are also relevant to costing. Why is this happening and why is the indicator not changeabe?.

Thanks,

Ariel