Topic: Error when posting OFX 211 document to banks server

I am posting a request to the banks server using OFX 2.1.1 XML and I am recieving an error in the response.:

Length cannot be less than zero.%0d%0aParameter name: length

Can anyone shed some light on this? Is there any documentation with better samples for OFX 2.1.1?

Thanks
GK