CREATE DATABASE permission denied in database 'master' after logon

Sorry maybe this is not a right thread.
I made a simple web site using MVC 3 and DefaultMembershipProvider to manage users. In localhost all work fine and I can correctly logon to a restricted area. After deploy if i try to logon on resctrited area i'll obtain the following error. 

[SqlException (0x80131904): CREATE DATABASE permission denied in database 'master'.] System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) +2074350 System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) +5066444 System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() +234 System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) +2275 System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async) +2 ...