The Command Or Action ApplyFilterSort Isn't Available Now.

I have created a search window that looks up certain invoicereport by invoice No. I have used this search method in other forms and has worked successfully!

However,
after I created the same thing for a report, I get this message: The Command or Action 'ApplyFilterSort' isn't available now.

I really don't understand the problem.
txtSearch = a textbox where user can type in any value to lookup a certain report.
rptInvoice = where I want the search to be placed.
fraSearch = an option group with (Starts with...,Contains...,Ends with..., Equals...)
InvoiceNo = the txtField in rptInvoice.

this is what I wrote for the cmdSearch button:

Private Sub cmdSearch_Click()
On Error GoTo Err_cmdSearch_Click
Dim strFilter As String
Dim strInvoiceno As String

' Check that the report is open
If SysCmd(acSysCmdGetObjectState, acReport, "rptInvoice") <> acObjStateOpen Then
MsgBox "You must open the report first."
Exit Sub
End If
' Build InvoiceNo criteria string
If IsNull(Me.txtSearch.Value) Then
strInvoiceno = "Like '*'"
Else
Select Case Me.fraSearch.Value
Case 1
strInvoiceno = "Like '" & Me.txtSearch.Value & "*'"
Case 2
strInvoiceno = "Like '*" & Me.txtSearch.Value & "*'"
Case 3
strInvoiceno = "Like '*" & Me.txtSearch.Value & "'"
Case 4
strInvoiceno = "= '" & Me.txtSearch.Value & "'"
End Select
End If

' Build filter string
strFilter = "[invoiceNo] " & strInvoiceno

' Apply filter to report
With Reports![rptInvoice]
.Filter = strFilter
.FilterOn = True
End With


DoCmd.DoMenuItem acFormBar, acRecordsMenu, 2, , acMenuVer70

Exit_cmdSearch_Click:
Exit Sub

Err_cmdSearch_Click:
MsgBox Err.Description
Resume Exit_cmdSearch_Click

End Sub
----
Could anyone help me with this?