Multiple Tables Used In Select Statement Makes My Update Statement Not Work?

I am currently having this problem with gridview and detailview. When I drag either onto the page and set my select statement to pick from one table and then update that data through the gridview (lets say), the update works perfectly.  My problem is that the table I am pulling data from is mainly foreign keys.  So in order to hide the number values of the foreign keys, I select the string value columns from the tables that contain the primary keys.  I then use INNER JOIN in my SELECT so that I only get the data that pertains to the user I am looking to list and edit.  I run the "test query" and everything I need shows up as I want it.  I then go back to the gridview and change the fields which are foreign keys to templates.  When I edit the templates I bind the field that contains the string value of the given foreign key to the template.  This works great, because now the user will see string representation instead of the ID numbers that coinside with the string value.  So I run my webpage and everything show up as I want it to, all the data is correct and I get no errors.  I then click edit (as I have checked the "enable editing" box) and the gridview changes to edit mode.  I make my changes and then select "update."  When the page refreshes, and the gridview returns, the data is not updated and the original data is shown.
 I am sorry for so much typing, but I want to be as clear as possible with what I am doing.  The only thing I can see being the issue is that when I setup my SELECT and FROM to contain fields from multiple tables, the UPDATE then does not work.  When I remove all of my JOIN's and go back to foreign keys and one table the update works again.  Below is what I have for my SQL statements:
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SELECT:
SELECT People.FirstName, People.LastName, People.FullName, People.PropertyID, People.InviteTypeID, People.RSVP, People.Wheelchair, Property.[House/Day Hab], InviteType.InviteTypeName
FROM (InviteType INNER JOIN (Property INNER JOIN People ON Property.PropertyID = People.PropertyID) ON InviteType.InviteTypeID = People.InviteTypeID)
WHERE (People.PersonID = ?)
UPDATE:
UPDATE [People] SET [FirstName] = ?, [LastName] = ?, [FullName] = ?, [PropertyID] = ?, [InviteTypeID] = ?, [RSVP] = ?, [Wheelchair] = ? WHERE [PersonID] = ?

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The only fields I want to update are in [People].  My WHERE is based on a control that I use to select a person from a drop down list.  If I run the test query for the update while setting up my data source the query will update the record in the database.  It is when I try to make the update from the gridview that the data is not changed. 
 If anything is not clear please let me know and I will clarify as much as I can.  This is my first project using ASP and working with databases so I am completely learning as I go.  I took some database courses in college but I have never interacted with them with a web based front end.  Any help will be greatly appreciated.
Thank you in advance for any time, help, and/or advice you can give.

Brian