CRM 2011 - How to check if SystemUser is Disabled

Question

I'm writing a script (VBScript) to create/update SystemUser in the CRM by importing the required information from one of our SQL table. Everything works fine but the update of the BusinessUnitId field.

The problem is the CRM restrict the ability to do so for disabled user. And by default all my users are disabled (they serve more as contacts than user, only a few of them are actually enabled). My question is fairly simple: how do I check if the user is enabled or not ?

StateCode and StatusCode are only made to set a user to enabled or disabled. IsDisabled field in the Systemuser CRM table seems unreadable (I get an key does not exist error if I try to read from it).

I'm really stuck here. Any ideas ?

Thank you

Update 3/11/2014 (Code as requested)

Try 1 - Always Return True even when it should be False
If (user_new.Contains("isdisabled") And user_new.GetAttributeValue(Of Boolean)("isdisabled") = False) Then
  Console.WriteLine("ENABLED")
Else
  Console.WriteLine("DISABLED")
End If

Try 2 - Key does not exist
If (user_new.Attributes("isdisabled") = False) Then
  Console.WriteLine("ENABLED")
Else
  Console.WriteLine("DISABLED")
End If

Try 3 - Key does not exist
If (user_new.FormattedValues("isdisabled").ToString() = 0) Then
  Console.WriteLine("ENABLED")
Else
  Console.WriteLine("DISABLED")
End If

Answer 1

BusinessUnit, Equipment, Organization, Resource and SystemUser all use the IsDisabled field instead of the standard StateCode and StatusCode. It should be stored as a boolean. Make sure that you include it in your ColumnSet when you retrieve the SystemUser from CRM