Macro works in Windows XP but not in Windows 7

[Baldeagle]

I have used a Macro called EmailMergeWithAttachments which was brought to my attention last year by macropod when he referred me to http://word.mvps.org/FAQs/MailMerge/...ttachments.htm which was created by Doug Robbins. This has worked on my computer which runs Windows XP. But when I try to run it on a laptop which is running on Windows 7 it throws up an error at "Dim oOutlookApp As Outlook.Application" - see the first section of the Macro below.

Is there any obvious reason why this Macro won't work on a laptop running Windows 7? Is this a known gremlin when you upgrade? Can anything be done to make it work in Windows 7?

I would appreciate some guidance.

Sub emailmergewithattachments()
 
Dim Source As Document, Maillist As Document, TempDoc As Document
Dim Datarange As Range
Dim i As Long, j As Long
Dim bStarted As Boolean
Dim oOutlookApp As Outlook.Application
Dim oItem As Outlook.MailItem
Dim mysubject As String, message As String, title As String

[Baldeagle]

Just by way of clarification - the message that appears is "Compile Error - User Defined Type not Defined".

Does this throw any light on the problem?

[macropod]

Have you set a reference to Outlook, via Tools|References?

[Baldeagle]

Thanks for the suggestion. Unfortunately my colleague is away for a month and I won't be able to check this until he returns - it was his laptop that I had the problem with. The reference for Outlook is ticked on my PC so I will check this when he returns.