IllegalAccessError when calling a WebService

Hi all,

i created a WebService with Developer Studio and i deployed it on SAP Portal EP 6.0 SP9, but when i call it with Enterprise Portal Web Services Checker i have this response: "The User Authentification is not correct to access to the Portal Service com.sap.portal.prt.soap.SV_MetaDataSet or the service was not found."

In the detail error the type is: "java.lang.IllegalAccessError".

I tried to insert the property SecurityZone in the portalapp.xml and i tried to modify the permission in System Administration --> Permissions --> Portal Permission --> Security Zones --> myWebService but nothing happens.