Okay, got it working now. I've kept the Dlookup, and for the ONCLICK event for SAVE command button, I've added the following code:
Code:
Private Sub cmdSaveRecord_Click()
If DCount("controlnumber", "tbl_Claim_Overview", "[controlnumber] = '" & Me.[Control Number] & "'") > 0 Then
DoCmd.SetWarnings False
Dim string1 As String
string1 = "UPDATE tbl_Claim_Overview" & _
" Set MyTable.claimoverview = '" & Forms![MYFORM]![ClaimOverview] & _
"' WHERE MyTable.[controlnumber] = '" & Forms![MYFORM]![Control Number] & "'"
Debug.Print string1
DoCmd.RunSQL string1
Else
DoCmd.RunSQL "INSERT INTO MyTable (controlnumber, claimoverview)" & _
" VALUES(forms![MyFORM]![control number],forms![MYFORM]![claimoverview])"
End If
DoCmd.SetWarnings True