I have .mdb database, and code like this:
.mdb
using (OleDbConnection connection = new OleDbConnection(myConnectionString)) { using (OleDbCommand
It is most likely the WHERE clause of your update statement isn't locating any records to update.
http://weblogs.asp.net/stevewellens/archive/2009/10/16/why-sql-updates-fail-three-reasons.aspx