Print Report From Form Based On Multiple Criteria?

Hi,

I have the following code which i found on another thread on this forum (thanks to original author) which is attached to the On Click of a button which prints the report corresponding to the details displayed in the form.

Dim strCriterion As String
Dim strMsg As String, strTitle As String
Dim intStyle As Integer

If IsNull(Me![ReferenceNumber]) Then

strMsg = "You cannot print a Blank Form!!."
strTitle = "Print Error"
intStyle = vbOKOnly
MsgBox strMsg, intStyle, strTitle

Exit Sub
End If

If Me.Dirty Then
Me.Dirty = False
End If

strCriterion = "[ReferenceNumber]=" & Me![ReferenceNumber]
DoCmd.OpenReport "DoC Certificate", acViewNormal, , strCriterion

This works fine, however, i need to be able to select the report based on more than 1 criteria. For example, the Reference Number can be repeated but is distinguishable from each other by an Issue Number i.e. ReferenceNumber = 93, Issue 1 or 2 etc. At present when i run the above it prints all versions of, in this case, reference number 93, which given that each report is only a single page isn't a show-stopper but it would be nice to have it working as i would like.

I have tried adding to the strCriterion line such as strCriterion = "[ReferenceNumber]=" & Me![ReferenceNumber] and "[IssueNumber]=" & Me![IssueNumber] but no joy. I have tried bracketing the whole line and variations thereof, again no joy.

Can anybody tell if what i am attempting to do is possible and if so how do i go about it?

I have tried the above coding using MasterID which is the Autonumber PK but it produces an "Enter Parameter Value" box for MasterID. Obvioulsy if i can get it to work for the Autonumber then my problem goes away but i can't seem to figure out why it works for Reference Number (Number) and not MasterId (Autonumber)?

Regards

Alan