Lookup - how to do this

[jilaba]

There are two sheets, sheet 1 and sheet 2
Sheet 2 already has some entries.
Now i want to enter some alpha-numeric values in sheet 1.
What i want now is, if the value being entered is found in sheet 2, it

should not be allowed to enter.
ie. while entering, it should automatically search in the given range of

sheet 2 and if the value is already there, it should give warning or

ZERO as answer.

how to do this?

Thanks.

[Jonmo1]

Do want to actually prevent the entry if it already exists on the other sheet?
Or do you just want to have a warning message in the adjescent cell?

For just the warning messing in the adjescent cell (B2 on Sheet1 of your posted book)
=IF(ISNUMBER(MATCH(A2,Sheet2!$A$2:$A$7,0)),"Warning","")

[wfm007]

I think is what you are looking for.....

[jilaba]

Thanks for those who helped.