Nav to Magento error -- 2

We have a 3rd party developer who is working on a connector between Nav and our Magento installation but he is receiving the following error: [login to view URL]: Procedure 'login' not present Server stack trace: at [login to view URL](ProxyOperationRuntime operation, ProxyRpc& rpc) at [login to view URL](String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout) at [login to view URL](IMethodCallMessage methodCall, ProxyOperationRuntime operation) at [login to view URL](IMessage message) Its not a big job to solve as our last developer sorted it very quickly We need it resolving urgently