Error after executing WS from FM

Hello all!!

I'm having some problems executing a FM after exposing it as a webservice. I have a Function Group where i have some useful FM's and never had a problem exposing them until yesterday. When I go to WS Navigator and try to execute it, the following error msg appears:

HTTP/1.1 500 Internal Server Error
content-type: text/xml; charset=utf-8 
content-length: 453<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"><soap:Body><soap:Fault><faultcode> soap:Servidor </faultcode><faultstring xml:lang="en"> RABAX ocurrido en el lado del servidor </faultstring><detail><sap:Rabax xmlns:sap="20130710093122SYNTAX_ERRORhttp://www.sap.com/webas/710/soap/runtime/abap/fault/generic"><SYDATUM>20130710</SYDATUM><SYUZEIT>093122</SYUZEIT><ERRORCODE>SYNTAX_ERROR</ERRORCODE></sap:Rabax></detail></soap:Fault></soap:Body></soap:Envelope>

As I said, this never happened before. Even whe i try to execute the FM ZWAPI_WF_END (the one where i cerated the WS) it in SE37, this error appears:

Sorry about attaching the error as an image, but i had some problems with my laptop and the time is precious right now.

Regards IA