[AccessD] Form as Subform - Query Fails - Why?

Hi,

Probably I am missing something but I don't understand why this bright 
idea of mine didn't work.  Here's the picture:

I have a little calendar form with textboxes BeginningDate and 
EndingDate.  I have a little parameter query that uses a date range set 
Between BeginningDate And EndingDate to select the appropriate records.  
The query creates a table of records of people who have made 
contributions within the date range.  This table is the data source for 
a Word document, the acknowledgement letter.

I thought I'd be really clever and make a form with instructions - 
"select the beginning and ending dates on this calendar"   "click this 
button to create the acknowledgement table" etc.  So, I plugged the 
calendar form in as a subform on this clever instruction form, rather 
than popping open the calendar form.  Setting the beginning and ending 
dates in the calendar, once it was a subform, did not provide the query 
with its parameters.  

I played around with setting the dates on the calendar-form-as-subform, 
then opening the calendar form independently - the dates were not set in 
the independent form, only in the subform.  So, clearly, the instance of 
the calendar-form-as-subform to the instruction form is a new beast - 
sort of.  Making design changes to the calendar-form-as-subform, such as 
background color, applies those changes to the independent calendar 
form.  But, setting textbox values from within the 
calendar-form-as-subform does not set those values in the independent 
form.  Do I really have two beasties here?  If so, why can I not find a 
way to identify the textboxes in the subform so my query can use them?

It looked like such a nice idea!  What am I doing wrong?

Thanks,
Tina