Error message: "Compile error. User-defined type not defined"

Hi,
I am trying to get an Excel sheet to read/write to an Access DB. My code starts as shown below.
When running it, I get the error: "Compile error. User-defined type not defined" - it crashes on the "Dim cnn As ADODB.Connection" line. I also notice that while String and Integer are syntax highlighted in blue, Range, ADODB.Connection and ADODB.Recordset remain black. I am guessing that my VB doesn't know how to interpret the ADODB commands.
In tools-references, Microsoft DAO 2.5/3.51 compatability library is selected.

Any thoughts on how to solve this would be welcome.

Lotte

Private Sub Worksheet_Change(ByVal Target As Range)
        
    Dim DBFullName As String
    Dim TableName As String
    Dim TargetRange As Range

    
    Dim cnn As ADODB.Connection
    Dim rs As ADODB.Recordset
    Dim intColIndex As Integer
     
    DBFullName = "Qa.mdb"
    TableName = "Tasks"
    TargetRange = "A3"

...