SSAS Tabular Model Error: Capacity exceeds maximum capacity

Parameter name: capacity

My table has 320 columns, so I checked the maximum limits on table size and found the following.

http://msdn.microsoft.com/en-us/library/ms365363.aspx

I'm well within the limits.

I already have another table in the same schema with 320 columns. So perhaps there is a limit on the total number of columns in the schema?