Promodel downtime at machines

helloguys. I'm having trouble with routing entities if one machine is down. I have 3 location,2 entities. A machine processes type-1 parts, and B machine processes type-2 parts, and then, they send the parts to c machine. I set the all locations, distributions, entities, and describe the downtimes of the machines. My question is, when A machine is down, i have to sent type-1 parts to B machine. After A machine is fixed, type-1 parts have to go machine A and never processed in B machine. I used DownQty function, but when machine A is down never process type 1 again. I want to do if (A_machine==down) type_1 go to B_machine. But i couldnt manage to code this if clause logic. If you help me, i will be so happy. Thanks..