Error code: 9214 Text: An error occurred while processing web service

Hi,

I am struggling with an error for an outbound web service. At the moment the web service is successful some of the time and fails some of the time. Basically when a bunch of messages get processed together some of them fail. The messages are being sent from SAP to Biztalk and return this error:

The return code is: 9214

Text: An error occurred while processing web service.

Any ideas or advice as to what this is and how it could get resolved? Very frustrating.

Thanks.

Regards, Martin.