A couple of things;
1) I have been troubled with dates in the past when working with SQL queries, so I always past dates in like '2010-Sep-10'
2) I notice in the SQL text you are adding a "" to the right?
Have you dumped the SQLtext to the output window to see exactly what the query text looks like?
I would write the statement above as;
xSQL = "SELECT * FROM sales WHERE SalesDate > '" & Format(Me.dtFromValue, "yyyy-MMM-dd") & "' AND SalesDate < '" & Format(Me.dtTo.Value, "yyyy-MMM-dd") & "';"
Also, you may want to look at creating paramaterised queries.