I set up a form with a drop-down list that pulls user names. It started out simply:

SELECT FullName,FullName
FROM dbo.CMS_User

This works fine, but I needed to hide users that are marked as "hidden". So I tried this:

SELECT FullName,FullName
FROM dbo.CMS_User
WHERE UserIsHidden = 0

That leaves out hidden users in the dropdown list as it should, but the names are out of alpha order. So I tried this:

SELECT FullName,FullName
FROM dbo.CMS_User
WHERE UserIsHidden = 0
ORDER BY FullName

I believe this is proper SQL-- it works in a MS SQL Server query, but the page that shows the form gives this error:

[Error loading the FormControl '']
[DataConnection.HandleError]: Query: Select FullName,FullName from dbo.CMS_User where UserIsHidden = 0 Order by FullName: caused exception: Ambiguous column name 'FullName'.

How can I get this working?

Thanks for your help.