vb.net linq dtb.AsEnumerable not available

If I create a new project and trying to set dtb.AsEnumerable in my linq query and it works. In an existing project its underlined in blue and states "is not a memeber of system.data.datatbale". I'm importing system.linq. The only difference is the target .net framework is set to .net 4.0 and the one where it worked was set to .net 4.0 client profile. Tried in my working projet and it works with either framework option.

Dim dtb As DataTable

        dtb = GetTable()

        Dim query =
            From record In dtb.AsEnumerable
            Select record