Power query previous non consecutive date

Hi,

I was trying to return a value from previous non consecutive date;

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so this gives me the third value in the list, so I thougt if I just added an index and used that it should work, but I keep getting an error

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I have thought about first bring back list of dates and then taking the max value, as that will aways be the latest but can someone say why the index retruns and error

RD