Data Filter and Vlookup

[MikeyZ]

Here's my Fx:
=('Daily Worksheet'!M643*VLOOKUP(K643,Sheet2!A:D,4,FALSE))

This formula populates O2:O1000
The sheet is initially sorted from A-Z , Col "E"
Data Filter is on all Headers.

Example.
after a sort on "N" I will have
=('Daily Worksheet'!M686*VLOOKUP(K643,Sheet2!A:D,4,FALSE))

or, after another sort on "E" I will have ,
=('Daily Worksheet'!M643*VLOOKUP(K643,Sheet2!A:D,4,FALSE))
back to nirmal.

if I sort on "D" I get
=('Daily Worksheet'!M698*VLOOKUP(K643,Sheet2!A:D,4,FALSE))

Why does the "M" value change.

Mike