I'm processing data in a very large data file and have multiple data files to
process. To expidite the process I want to use VLOOKUP to lookup a time stamp
and return cooresponding row indices. I've accomplished this suing the
formuals below:

=VLOOKUP(H8,Data!$B$5:$T$64000,19); returns 455 from an index row in the
imported data file.

Now I want to automatically update the X & Y range series in multiple
charts. I tried to do this with the formula below that works in a worksheet
cell but it gives me en error when I paste the formula in the X or Y series
box of the chart.

=("Data!B"&INDEX(J8:K13,1,1)&":B"&INDEX(J8:K13,1,2 )); returns Data!B455:B1355
where 455 is located in cell J8

Can anyone suggest a way to accomplish what I'm trying to do?

Thanks,