There are two ways to handle this, depending on your comfort level and access to the data source.

One is to use a stored procedure inside your database.  You can use a SQL  Command object instead, but it's tricky to make it work right with parameters and whatnot.  You would put the date restrictions for the LABTRANS table in the JOIN statement, rather than in the WHERE statement.  This is the ideal solution.

The other solution is to allow your report to pull all of the data (i.e., don't reference LABTRANS in the Select Expert at all), but suppress any records that are outside the date range.  The main disadvantage here is that you will have an impact to performance, as you are pulling in every record from the LABTRANS table for that supervisor.

I can get more detailed on the solution, if you would like.

There is a caveat to Hilfy's suggestion, though.

If there is a record in LABTRANS that exists for the supervisor, but not one that falls within the date range, then no records will be returned.  There is neither a record within the date range, nor will the outer join generate a NULL value, because there is a matching record in the join.