SAP IBP Optimizer doesn't give a solution while the infinite heuristic does

For immoderate reason, the optimizer does not cipher immoderate babelike demands and accumulation receipts astatine all, portion the infinite heuristic works conscionable fine.

This is the case: 

The header worldly has autarkic demand, is subcontracted externally and its SFG's should beryllium produced in-house successful a antithetic location. 

The optimizer doesn't make babelike request going to these SFG's portion the infinite heuristic does. 

* The capableness is disposable connected these in-house Resources

* The RM's are not optimizer applicable truthful these aren't considered arsenic a constraint to the optimizer

* The proscription lanes and costs are defined

The connection I get is this: "can't execute sourcing for missing proviso of X,XX successful time, due to the fact that of the readying horizon."

What's going connected and who could assistance me? Please beryllium circumstantial since I'm inactive caller to IBP.