We have a vlookup formula which does not seem to recognise that a number in our table array is the same as the lookup value (by sight to about 20 decimal places).

If we link to another spreadsheet and in that spreadsheet subtract the value in the table from the lookup value, then mulitply the result by 10^14, it returns a value of 0.07 and we think this is why the vlookup isn't returning the correct value.

I guess the question is:
a) Is there a known problem with the vlookup function when numbers appear to be the same

or

b) Is there a problem with "noise" in our spreadsheet. I've heard of the concept before, but haven't seen it's effect for a long time. If someone can give me an explanation for this phenomonon I would be very grateful. I have a dim recollection of this being a problem with excel, but I'm having a job explaning it to my Director (who is obviously livid that we have a scorecard with an "error" in it).

Many Thanks!!!