Hello Mario,
Have you published the corresponding service?
See
http://wiki.sdn.sap.com/wiki/x/OYG8BQ
Check the core ITS Services, WEBGUI, SYSTEM, ITSMobile, ITSGENMOBILE,
ITSGENMOBILE4, ITSGENMOBILEXV and IAC
And have you used the ITSMobile logon class for your Mobile service? Open the corresonding service and goto the Error Pages tab and click on change mode button. Click the
Configuration button and choose Define Service-Specific Settings. In
the Logon Layout and Procedure section select the Custom Implementation
radio button and in the ABAP Class field type in CL_MOBILE_SYSTEM_LOGIN.
Best regards,
Yuki