I think, that dates in columns L are no dates. They are the text. They only look like dates. There is effect of import of data from other base (probably).
Before You run [Search Date], you must "translate" text on dates.
1. Select data in column L.
2. From menu select Data/Text to columns... (sorry, I have polish version) )
3. In first step select "divided" and no [Next], but [End]
Several errors are in procedure cmdSearch_Click.
My proposal:
Sub cmdSearch_Click()
Dim dDatestart As Date
Dim dDatelast As Date
Dim ldatelast As Long
Dim lDatestart As Long
With Sheets("wdnsse")
.AutoFilterMode = False
.Cells(1, 13).Value = frmsearch.tbstartdate.Value
.Cells(1, 14).Value = frmsearch.tbenddate.Value
dDatestart = .Range("M1")
dDatelast = .Range("N1")
lDatestart = DateSerial(Year(dDatestart), Month(dDatestart), Day(dDatestart))
ldatelast = DateSerial(Year(dDatelast), Month(dDatelast), Day(dDatelast))
.Range("L2").AutoFilter Field:=12, _
Criteria1:=">=" & lDatestart, _
Operator:=xlAnd, _
Criteria2:="<=" & ldatelast
End With
End Sub
This procedure is not optimum and no error handling.
Artik