Using PostgreSQL transactions through MS Access?

I am trying to update my database with a big transaction so I don't get
an invalid state. My front end is in Access 97. Is there anyone out
there who does this that could tell me what I'm doing wrong? Here's my
code:

queryString = "BEGIN TRANSACTION;"
mdb.Execute queryString, dbSQLPassThrough

It tells me that it's an "Invalid SQL Statement". It seems like Access
is trying to parse it instead of sending it on to the DB server. I
thought that the dbSQLPassThrough was supposed to stop that. Does
anyone know where I went wrong?