Filter Main For Based On Subform Criteria

Hi,
I've posted this same question a few months ago, started something else and forgotten about the problem, now I really need to solve this! (I had no luck with the original post - code still not working).

I want to apply a filter to my main form based on criteria showing on a subform. This is the code I've got (applied to the OnOpen event of the main form):

Code:Private Sub Form_Open(Cancel as Integer)Dim stDocName As StringDim stLinkCriteria As String stDocName = "Campaign Form"stLinkCriteria = "[Forms]![Campaign - Last Contact Status subform]![Communication Response]=1" DoCmd.OpenForm stDocName, acNormal, , stLinkCriteria, acFormPropertySettings, acWindowNormalEnd Sub

The main form is called Campaign Form
The subform is called Campaign - Last Contact Status subform
The field I want to filter on is Communication Response

The criteria I want to filter is : I only want to show records from the Campaign Form (main form) where the status of the Communication Response on the Campaign - Last Contact Status subform (subform) is equal to 1.

I've tried a few variations of the above code but the results are always the same - prompting to enter a paramater value. Now I'm just fishing and hoping I'll get it right.

FYI. the subform only contains one record for each record on the main form. It works a bit like this :
Customer||Date||Communication Response(1=open, 2=closed)
One||20/4||1
Two||21/4||2
Three||21/4||1
One||23/4||2

The corresponding record on the subform for customer One will show the communication response of 2 as this is the most recent date. Therefore you now have the following :
Customer||Communication Response
One||2
Two||2
Three||1

Now I want to only show those records that have a Communication Response of 1. Remember this field appears on a subform. This is the part I am having trouble coding.

I know I've probably just explained the most irrelavent details but if anyone can help me it would be greatly appreciated!!