REST -> SAP PO -> Abaproxy Error SAP PI/PO

Hello Experts, I have a question about a REST -> PO -> Abaproxy integration. There are already several times that I find that an interface gives an http 500 error when connecting to SAP, and this same interface if I put an external breakpoint on R3 and I debug it, it works. Do you know what could be happening? Thanks on advice. David.