[AccessD] Drew - TreeView help again, please

Hi Drew,

First of all, thank you very much for getting me started using the 
TreeView control.  I can see that this will be very useful - but, I am 
still struggling to get my brain around it.

I have very carefully worked through your code and made the name 
adjustments I have to make to match up to my existing tables and 
fields.  There are still a couple of places where I scratch my head and 
say "huh?" but for the most part I am finally understanding what you 
have shared with me.  Thanks.

Now, I have run into a runtime error that I don't understand and I don't 
know how to handle.  When I select a volunteer from my combo 
(cboVolunteers), I get this error message:
---------------------------------------
Run-time error '-2147217904(80040e10)':
No value given for one or more required parameters.
----------------------------------------

When I click the Debug button, the line of code that is highlighted is:
-------------------------------------------------------------------------------
rs.Open strSQL, CurrentProject.Connection, adOpenKeyset, adLockReadOnly
-------------------------------------------------------------------------------

I have no idea at this point what is wrong.  Can you help me figure it out?

Thanks,
Tina