Problem with Barssince with AddColumn

Why is BS giving me different values ? The value in Title is correct. AddColumn is wrong ...

When replacing Barssince(Buy) with something like 25, values are correct. I don't get it ... Also LastValue from Barssince(Buy) does not give a correct result.

//+++++++++++++++++++++++++++++++++
// Plot and Report area
// +++++++++++++++++++++++++++++++++
// Scan/Explore ...
// Get number of days since BUY and check
// if we want to go back sofar ...
Filter = 1;
BS = Barssince( Buy );
AddColumn(BS,"Bars since Buy");
Title = "Bars since Buy = " + BS;

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