battery interference?

I've recently been out sourcing a project for my major project at university. It basically involves a servo that rotates 180 when activated by an RFID card. The problem I'm having is that it all works fine until I put the battery and the PCB near each other, then it stops working. Could it be interferes with the RFID reader?
Oh and I'm new to this so layman's terms, if you please! :-/