Filters not working as expected

Hi guys, I am trying to create a simple dymanic filer based on computer name.  I used the query builder and it is pulling in more results than I want.

Want to filter by name starting with DEN.

Have my query setup as Computer including Windows Workstations

Added a Parameter with value DEN%

And set the filter to use it.

Am getting computers that's name do not start with DEN and ones that start with DEN.  HELP.  :)

Thanks

Ash