Contract Billing Invoice has error messages

Hello,

I need your help please. I have set up a customer with USD currency and Base Currency being blank (CAD). My Contract Master is set up the same base CAD and USD foreign. I get the "out of balance" in work center error when creating A/R, my Journal Edit register shows just the one side entry of CAD. the G/L journal Generation is saying No Transaction were selected for G/L Batch, batch not created. Please tell what I am missing?

Thanks Susan