Find Date row error on Find

I have an odd problem that I have noticed on two worksheets. I have a sheet with dates for the year entered in column A3 and down, starting at 1/1 and going to 12/31. I then have a userform where the user selects a date from a DTPicker and the macro locates the row for the selected date to perform various functions in that row. The problem I have is that when 1/1/YY is selected, the find method always selects the row for date 11/1/YY. I have no idea why it does that and have to manually correct for it ATM. Any insight would be appreciated.

[VBA]Sub Update_Charts_bydates(DtStart As Date, DtEnd As Date)

Dim Ws_1 As Worksheet, Ws_2 As Worksheet
Dim Ch_1 As Chart, Ch_2 As Chart
Dim rngTATdata As Range, rngTATlabels As Range, rngRFTdata As Range, rngRFTlabels As Range
Dim iDtEnd As Integer, iDtStart As Integer

Application.ScreenUpdating = False

Set Ws_1 = Worksheets("Historical") 'sheet with dates entered down starting at A3
Set Ch_1 = Charts("TAT")
Set Ch_2 = Charts("%InSpec")

Set DateHeader = Ws_1.Range(Ws_1.Range("A3"), Ws_1.Range("A3").End(xlDown)) 'set range to find date

On Error GoTo ErrHandler
If Month(DtStart) = 1 And Day(DtStart) = 1 Then '1/1/YY likes to find 11/1/YY instead, so manually correct
iDtStart = 3
Else
iDtStart = DateHeader.Find(DtStart).Row
End If
iDtEnd = DateHeader.Find(DtEnd).Row

'---------------- More code below but not shown
On Error GoTo 0[/VBA]

If you really want to see the sheet I can attach a desensitized version upon request

I tried playing with the full settings but kept getting an error code of 91 "Object variable or With block variable not set". Not really sure why since nothing really changed. On another workbook I have basically the same setup but starting at A2 with the same issue. It's almost like it doesn't actually see the 1/1/YY

Sorry I misunderstood what you meant. By changing the start of the range from the first cell to the header it now works. I find that odd that it would not search the first cell of the range since it is part of the search area. I tried messing with the after parameter but kept getting that error code of 91.

thanks for the help NoSparks