Stopping duplication within Data validation

[SNA400]

I hope someone can help me with these problems!

I am using Data Validation for selected vehicles on runs, but I need to stop
people assigning a duplicate registration for seperate runs.

The list for the data validation is in cells D91 to D120 and the entries are
made in cells H3 to H47

I have tried the following:
(Cell H2)
=ISERROR(MATCH(H2,H3:H47,0))
(Cells H3 to H47)
=ISERROR(MATCH(H3,INDIRECT("$D$91:$D$120"ROW()-1),0))

But validation throws a wobbly and doesn't like the entry (which is exactly
as I copied from help!)

Where am I going wrong??

ALSO - on the same sheet I need to stop people using the vehicle
Registrations from the validation in cells H48 to H60 - can I use the same
validation list or do I have to set it up again

PLEASE HELP ;-(
Simon

 

[Luke M]

In answer to your first part, it sounds like you want to hide previously used
entries. See Debra's aritcle:
http://www.contextures.com/xlDataVal03.html

Expanding on her idea, since your new list of values to use is created via
formula, it would be a relatively simpel matter to have the formula not show
values that are lsited in H48:H60.