Queries :: Query Not Returning Certain Data

I have 2 tables, one called Location and the other called PC Inventory. They both have columns called sites. The query is set to search both tables by site name and return the PC's at that site that match the search criteria.The search form has a drop down menu with all the site names. When you choose a site name from the last, the after update event does a re-query to a subform on that same form. The source object of the subform is set the query.[Forms]![PC Search]![Combo6] - this is the criteria on the query that point to the drop down menu.

Private Sub Combo6_After Update()
Me.Child19.Requery
End Sub

This is the requery that point to the subform (child19)..The problem is that some selections from the list don't return any results to the subform. But there is clearly records that meet the criteria in the table. Example: ABC @ Maryland returns all the PC's at the site. DEF @ Maryland doesn't return any PC's at the site, but there are records with that site name.Even if go into the table copy the site name that isn't working and enter into the search field it doesn't return the results.