Update, Items Not Found. Self Taught N Distraught

Ok, so I've inherited a db that was created in 97 and I had to convert to 2000. I've battled through all the DAO code issues and the new db works like a charm. Almost. It's an equipment tracking db in which many fields are tracked and updated. The action in question updates those fields in one shot. example a piece comes back from repair and I want to place it back in stock, change status from "maint" to "rfi", and update dates. It also works the opposite way. But it's the same thing. Regardless, when I get to the point of updating I get the "Item is not found in this collection". So now I'm stumped because I'm not sure what I need to add to make this work. Here's the code (note, I removed the .edit lines. Didn't change anything) One question is, what line in this code allows the item to be found? And why won't it find the item in my 2000 version? Again, I get no errors in the code, I just can't seem to connect this update to my db (I guess that's what I'm saying):

Private Sub Command21_Click()
On Error GoTo Err_Command21_Click
Dim Msg As String
Dim Response
Dim stDocName As String
Dim db As Database, rs As Recordset
Dim strSerial As Integer
Dim strRepSerial As Integer

Msg = "This will update this device's Status. Are you sure you wish to continue?"

Response = MsgBox(Msg, vbYesNo + vbExclamation)

If Response = vbNo Then
Exit Sub
Else
If Me!Status = "Maint" Then
Dim stDocName2 As String
Dim stLinkCriteria As String
stDocName2 = "frmRecertDate"
stLinkCriteria = "[Serial#]=" & Me![Serial#]
DoCmd.OpenForm stDocName2, , , stLinkCriteria
End If
DoCmd.SetWarnings False

DoCmd.OpenQuery "qryReplaceSerial#'s"
DoCmd.OpenQuery "qryStatusIssued"

DoCmd.SetWarnings True

'get Serial# of device selected for return to stock
strSerial = [Serial#]
Set db = DBEngine.Workspaces(0).Databases(0) ' Get current database.
Set rs = db![Total Device Listing].OpenRecordset() ' Open table.
rs.Index = "PrimaryKey" ' Set index."
rs.Seek "=", strSerial

If Me!Status = "IT/Return" Then

DoCmd.SetWarnings False
DoCmd.OpenQuery "qryClearRepl"
DoCmd.SetWarnings True
With rs
.Edit
!devicecReturned = True
!Status = "RCR"
!Recall = Null
!Location = "holding"
!Acct = "123421"
rs.Update
Refresh
rs.Close
End With
Else
With rs
.Edit
!deviceReturned = True
!Status = "RFI"
!Recall = Null
!Location = "stock"
!Acct = "234234"
rs.Update
Refresh
rs.Close
End With
End If
End If
Exit_Command21_Click:
Exit Sub
Err_Command21_Click:
MsgBox Err.Description
Resume Exit_Command21_Click
End Sub