AutoFilter With block variable not set

Something very strange is going on.
I have a spreadsheet saved with an autofilter on.
I then call one method (via a button) which fills some data and does some filtering.
I then change one of the filtered (visible) cells from N to Y.
However, when I call the next method (via a second button) I get error 91 when trying to address the range
i.e.

Code:

---

Private Sub cmdDownload_Click()
    Dim rngFilter As Range
    Set rngFilter = Sheet14.AutoFilter.Range

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gives

Code:

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Object variable or With block variable not set

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Also checking AutoFilterMode returns false

Code:

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Private Sub cmdDownload_Click()
    If AutoFilterMode = False Then
        Sheet14.Range("B11").AutoFilter
    End If
    Dim rngFilter As Range
    Set rngFilter = Sheet14.AutoFilter.Range

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This then has the effect of REMOVING the autofilter that was previously on. (Because it thinks it is off when it isn't "Sheet14.Range("B11").AutoFilter" has the effect of turning it off instead of on)

If I put 2 such blocks, I end up with the AutoFilter displayed on screen.
However, I still get the error when I try to set my range. :confused:

An interesting development!
I actually inherited the original sheet and it looks like the autofilter is actually part of a List (or Table in 2007 parlance).
I've converted it to a normal range (i.e. got rid of it) and so far the problem hasn't recurred. :thumb: