Query question with form

I have created three queries. Each query is called sequentially and is dependent upon data from the prior query. The third query is invoked by a form. The user enters date parameters on the form, then clicks a button which invokes the third query (which calls the earlier query). Each query works fine when run independently, but when all three are run using the form, the second query returns the error message:

The Microsoft Jet Database engine does not recognize '[Forms]![ETP]![xEndDate] as a valid field name or expression'

When I ask to print the field in the immediate window, it shows up just fine. There are no misspellings. This field is only referenced in one query (the first query). The error shows up during the third query. If I substitute a hard coded date in the first query, no error occurs.

Help!!!!