Fill ListBox with specific columns from two worksheets

Starting at the beginning - your 'Set' SheetData and 'Set' Worksheet Appoint names do not reflect the actual worksheet names you have given.
from there it is all downhill - spelling ???? SheetData then becomes sheetData (upper case 'S' becomes lower case 's')
see big yellow banner - upload your workbook - far easier then to give you a working solution.

Hi all - I suggest you comment out or remove the first line...

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... and let VBA handle the errors normally. It will highlight the line where the error is occurring and display an error message, which might give you a clue.

@leelnich,I do not wish to sound condescending, the O.P. deserves more assistance than your suggestion.
A brief glance at the code illustrates a need for some in depth guidance as it is nonsensical, with elementary syntax errors, 'Set' names that do not tie up with declared names, the list is extensive.
That is why I have suggested he uploads his workbook so that we can guide him using his actual app at a 'single sitting' rather than committing to an extensive dialogue of guesses.