Can you tell us more about your environment, is this a new or existing install?
Are you using SQL 2008 or 2008 R2? SQL 2008 support was removed in TMS 14.6, TMS 15 only supports SQL 2012 and 2008 R2.
Suggest you take a look at the TMS 15.0 Install Guide to make sure the server and SQL is configured correctly prior to installing TMS.