Service reference error in Synchronous BPM scenario

Hello,

i am implementing a BPM scenario with an automated action that calls an iFlow.

The iFlow is SOAP to JDBC with an outbound SYNCHRONOUS service interface. The purpose is to make a lookup on a database and return a value.

Once i run the BPM I encounter the following error:

Process 'Pool 0' set to In Error

A technical error during invocation: Could not invoke service reference name 013ddc22-f243-4f3d-9104-e8138263b200, component name demo.sap.com~dcbpmsyn~BPMcomponent, application name demo.sap.com/dcbpmsyn   

We have already checked this document:

http://wiki.sdn.sap.com/wiki/display/TechTSG/Sending+a+message+from+SAP+NetWeaver+BPM+process+to+PI+fails+via+automated+activity

but everything seems to be fine.

Any idea or suggestion?

Thank you

Regards

Andrea