Lookup Value Code Broken... HELP!!

The following code is being used to pull in the Name from the previous record into the current record. It works GREAT for 28 records, and then it starts just pulling random names from the source table. Can you tell me what I'm doing wrong? Thank you!Private Sub Form_Current()

Dim s As String
Dim db As New ADODB.Connection
Dim rs As New ADODB.Recordset
Set db = CurrentProject.Connection

s = "SELECT Last(ERName) AS ERName FROM [Staffing]"

Set rs = New ADODB.Recordset
rs.Open s, db, adOpenDynamic, adLockOptimistic
'add to the table

With rs
Me![ERName] = .Fields("ERName")
End With
Set rs = Nothing
Set db = Nothing

End Sub