Hi
I think the problem with @Variable('BOUSER')..try with below syntax.
QUERY_BAND='Universe='@Variable('UNVNAME');Document='@Variable('DOCNAME'); BOUSER = '@Variable('BOUSER')';'For Transaction;
http://www.dagira.com/2010/06/08/using-connectinit-for-teradata-query-banding/
http://downloads.tableausoftware.com/quickstart/feature-guides/queryband_teradata.pdf