Error trying to Add to record using ADO

[blakemckenna]

I am trying to add a record to a SQL Server DB. I am using ADO. When I try adding the record, I get the following error message:

-2147217873: Violation of PRIMARY KEY constraint 'PK_tblClients'. Cannot insert duplicate key in object 'tblClients'.

I know the primary key is unique in this instance. I'm not sure what I'm doing wrong. I have attached the code below:

Private Sub client_IO()
    On Error GoTo ErrorProc
    
    If tblClients.State = 1 Then
        tblClients.Close
    End If
    
    tblClients.Open "tblClients", oConn, adOpenStatic, adLockOptimistic
    
    If tblClients.Supports(adAddNew) Then
        With tblClients
            .AddNew
            !cliClientID = txtClientID.Text
            !cliCommonName = txtCommon.Text
            !cliEmail = txtEmail.Text
            !cliAddr1 = txtAddr1.Text
            !cliAddr2 = txtAddr2.Text
            !cliCity = txtCity.Text
            !cliState = cmbState1.Text
            !cliZipCode = txtZip.Text
            .Update
        End With
    End If
End Sub