LDAP and AD

[talon]

I have made a little app that will search the active directory and pull up a user and let you edit the fields of the user and then update it, does anyone know why it would work fine on my computer but when I try to use it on another computer on the network some parts work, and others don't. For instance it can add new users to the AD fine, but when i go to edit them, change groups, enable/disable the account - i get a nice little "a constraint violation occurred" error, any ideas? if more info needed let me know.