I have a group of asset tags with corresponding serial numbers stored on a
spreadsheet called MasterList.

I have a second spreadsheet I use to track movement of my assets, called
OrderSheet:

Row Column N Column O
2 M503690 LX08ALF
3 M503529 LX08AD9
4 M504276 LX08478
5 M502127 LX0888Y

When an order is placed, I need to enter an Asset Tag into cell N6 of the
OrderSheet. Then I tab over to the next column and enter the serial number
into cell O6. I would like to use data validation to check that I have
entered a serial number that corresponds with the asset tag I previously
entered.

I have defined first cell of my MasterList as AssetStart, the first column,
which holds the Asset Tags as AssetList, and the second column, which
contains the serial numbers, as SNList.

If I use the formula =OFFSET(AssetStart,MATCH(N2640,AssetList,0),1)
in cell o2 I can pull the correct serial number (that matches N2), but the
file is imported into a csv, so that does not help me.

Can anyone help me with the data validation piece of this?

Thanks