Excel 2003:

Apologies if I am doing something incredibly stupid but its been a
very long month and way behind on a project and this is driving me
crazy!

references in sheet 1

B
2 84856
3 84857
4 377738
5 406787
6 406788

Same references in sheet 2 in a range named DC_Issues

B C
2 84856 1
3 84857 2
4 377738 3
5 406787 4
6 406788 5

Then in column J on Sheet 1 formula VLOOKUP(Bx,DC_Issues,2,TRUE)

Returns
J
2 1
3 2
4 2
5 2
6 2

Have confirmed that the formula has been copied down correctly. Range
defined. Yet whatever i do (and I have tried numerous things!) I
cannot get the right value to be returned. I have been using this
function for years and haven't come accross this before.

Any help greatly appreciated.