OBM and Prostructures

When you click the ProStructures button from inside OBM, it should start ProStructures and you should be able to use the OBM tools to place reinforcement in the model. But unfortunately is does not. Even though both programs are installed, it says ProStructures cannot be found. 

Are only certain versions compatible? Anyone know how to integrate the 2 programs?

Any help is appreciated, 

Thank you!