Cascading combo box and list box - no data selection

[yellowgelb]

Hi
I was reading a lot of posts but couldn't find an answer for my problem.
I' ve got a combo box (EveRegion) and a list box (Location). After choosing a region in the combo box the list box need to show all matching locations. Both boxes are unbound. The combo box got the following row source

SELECT Distinct tblLocation.LocRegionRef FROM tblLocation;

and no control source. The list box has neither a control source nor a row source. The form has no record source. I don't get an error. I am using the following code in the after update event of the combo box.

Private Sub EveRegion_AfterUpdate()
Dim strRS As String
  
  strRS = "SELECT tblLocation.LocLocation FROM tblLocation"


  If Not IsNull(Me.EveRegion) Then
    strRS = strRS & " WHERE LocRegionRef = " & Me.EveRegion
  End If
 
  Me.Location.RowSource = strRS
  Me.Location.Requery
 End Sub

When I stop the code and look at every line of the code it shows me that strRS has the correct content but the Me.argument at the end of the code is empty (Me.Location = ""). I am not sure if the error is in the code or in the settings of the properties.

I changed and tried a lot so I just don't now what else I could try. Probably it's a simple problem just can't see it. Very happy about every advice. Thanks.

[Bob Fitz]

Perhaps something like:

Private Sub EveRegion_AfterUpdate()Dim strRS As String
  
  strRS = "SELECT tblLocation.LocLocation FROM tblLocation"


  If Not IsNull(Me.EveRegion) Then
    strRS = strRS & " WHERE LocRegionRef = '" & Me.EveRegion & "'"
  End If
 
  Me.Location.RowSource = strRS
  Me.Location.Requery  End Sub

[yellowgelb]

Hi thanks for your answer.
I tried to work with different amounts of quotation marks, but still couldn't figure out the solution. I simplified the code as shown to see what the actual problem is.
When I choose a region (e.g. Desert) from the combo box (with the code below) Access is asking me "Enter parameter value" for Desert. And when I put quotation marks around Me.EveRegion it is asking for a parameter for Me.EveRegion. When I name again the same region I always get the correct answer.

But why is Access asking for a parameter? Is this only about wrong quotation marks or do I have another bug??

That's the code.
Debug.Print EveRegion is the region (e.g. desert)
Debug.Print Location is Null

Private Sub EveRegion_AfterUpdate()
Me.Location.RowSource = "SELECT tblLocation.LocLocation " & " FROM tblLocation " & " WHERE LocRegionRef = " & Me.EveRegion
Debug.Print EveRegion
Debug.Print Location
End Sub

Thanks a lot for your help!!.....I forgot to mention both data entries region and location refer to a string.

[yellowgelb]

Hi thanks again for the advice with the quotation marks. It's working now.