RFC_NO_AUTHORITY calling ABAP function from a Web Service

Hi,

We have a web service that publishes existing BAPIs, and some custom ABAP functions.

When calling the custom ABAP functions we a "system exception" in the client side. Looking at SM21 the log has a dump:

The user "1DDD8B960830" in the client 310 attempted to execute the function
  module
 "RFCPING" from the function group "SYST", but does not have the appropriate
 RFC authorization.

 Error in the ABAP application program.

 The current ABAP program "SAPLSYST" had to be interrupted because it contains
 a statement that cannot be executed.

We're on SAP-Release 710

Please take into account that RFCPING is not a function we're calling...

Any help would be appreciated

Edited by: Enrique VETERE on Jun 25, 2008 5:35 PM