"Project name already exist" when creating a new ant or shell project in a recently created project group

When trying to add a new shell project, it always gives this error:
"Project name already exist"
This happens for the first time. After that, the project exists, but when we try to modify it, throws a NullPointerException.
When executing the project, continuum ignores it. In the URL of the project execution request, we can see "projectGroupId=0", instead of the right group id, that in this case is "7".