Error on Print Flag Select:

The Northwind Contact sample bd has the label print functionality I need. I want to select each member and then have the Label Wizard activate. An expert suggested I link my table to the Contact db and edit several record source. Each member name and print check box is now displayed in the sub form...But

When I try to select one of my members print check box I get the following error message:

"Field 'PrintFlag' is based on an expression and cannot be edited"

When I select "Select All Contacts" I get:

"Form_PrintLabelSubs.ckSelect_AfterUpdate"
"3421: Data Conversion error"

Northwind record source for Print sub:
SELECT Contacts.ContactID, [FirstName] & " " & [LastName] & ", " & [CompanyName] AS Name, Contacts.LastName, Contacts.PrintFlag FROM Company INNER JOIN Contacts ON Company.CompanyID = Contacts.CompanyID ORDER BY Contacts.LastName, Contacts.FirstName;

My record source:
SELECT Members.EnvelopeID, [LastName] & " " & [FirstName] & ", " & [EnvelopeID] AS Name, Members.LastName, Members.PrintFlag FROM Members ORDER BY Members.LastName, Members.FirstName;


I only have one table. Do I need 2?