Hello, could you please open the ODBC Data Source and repoint to the DB again.
you have to choose the correct SQL Client Driver for sql 2012 
.
Because seems to be theire is something missing ;).
Just create System DSN again but with "SQL Server Native Client 11.0"
then test connection with you're created internal sql user or windows user. depending on you're config (mixed mode?)
PS: Please choose correct DB ;(
thx Max