Fixed an incorrect error message in the CyTable implementation.

Change-Id: Ib635a9dda0a55a9c6a0947a2d82b5d77edd0dca8
Fixes #1948: The session reader now recreates virtual columns in the correct order when they depend on other virtual columns.

Change-Id: Iea1e6d3ecab933f61d8412031b92d04af3645db7