Unexpected err=AssertionError(), type(err)=<class 'AssertionError'>

I get Unexpected err=AssertionError(), type(err)=<class 'AssertionError'> whenever l send a ProtoOAGetDynamicLeverageByIDReq() request to the server in python. It happens also when it is the only line of code executed. Has anyone experienced this issue? If so please could you give me some advice or comment on what to do to get round this issue. The content of function is as follows:

def sendProtoOAGetDynamicLeverageByIDReq(leverageId ):

    request = ProtoOAGetDynamicLeverageByIDReq()

    request.payloadType = ProtoOAPayloadType.PROTO_OA_GET_DYNAMIC_LEVERAGE_REQ.value

    request.ctidTraderAccountId = accountId

    request.leverageId = int(leverageId)

    deferred = self.client.send(request)

    deferred.addCallback(leverageResponseCallback)

    deferred.addErrback(self.onError)

    return deferred