I have problems using the IsPortalUser flag on the User object in Apex.

This line gives the error:

List<User>lstUsers=[select Id, IsActive, IsPortalEnabled from User where IsActive=true and IsPortalEnabled=true];

We are on Enterprise Edition with Customer Portal licenses in our org.

The select statement works in the Development Console and in the Eclipse Salesforce Schema query interface

Any ideas?

/Mats