How can I find the last colored and blank cell in a row using VBA in Excel 2010?

I am new to VBA and am writing a macro to find the last blank cell filled with a specific color on a specific row. Based on what I've read and tried so far:

• When trying to identify the last cell / row / column, it's best to start at the bottom or to the right.
• The Find method is faster than using a loop.
• Questions about (and therefore usage) Find
  
  focus on identifying the last row or column with (sometimes missing) data, or the last cell used (usually in a column and containing data).
• It is best to specify the interior color before using the method Find
  
  , because it can mean some other interior color from previous use (by code or user).

Here is the code I have so far:

Sub FindLastEmptyTurquoiseCellOnRow18()
Dim rngFindColorCell As Range
    Range("XFD18").Select
    With Application.FindFormat.Interior
        .Color = 16763955
        .Pattern = xlSolid
        .PatternColorIndex = xlAutomatic
    End With
    Set rngFindColorCell = Range("A18:XFD18").Find(What:="", After:=Range("XFC18"), _
     LookIn:=xlValues, LookAt:=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlPrevious, _
     MatchCase:=False, SearchFormat:=True)
    rngFindColorCell.Select
End Sub

      

        
        
        
      

    

The After parameter seems to be my newbie in explicit conflict with the search direction I want (after points to the right (?), xlPrevious

Says to go left). If the search really needs to start 1 cell from the right before going to the left, I've specified the next last cell in the row.

Also, I can probably limit the search for a row to the first 8785 columns.

I am trying at the end (use this time Select

) to determine if the code identifies the correct cell. It is at this point when I step through the code that I get the error:

Runtime error '91': object variable or with locked block variable

• How to determine if a code identifies the correct cell? (I tried MsgBox
  
  and set the interior color of the found cell to a different color, but also got errors.)
• Is there a bug in the code that prevents the correct cell from being identified?
• Should I use a method other than the Find method instead?

I look forward to (and would be very grateful) for any "gurus" cracking this little nut!