If functions: cross referencing lists between sheets

Hi guys,
I am an environmental scientist, and use Excel to help me work out which plant and animal species are protected. On one sheet I have a list of all the species that are protected, and on another I paste in a list of all the species that I found on the site. I have set up a formula to check the 'pasted' list against the 'protected' list on the other sheet, and if a species is protected then it flags it up.

This works fine, however it only works for the first 263 records - if a species is listed in row 264 or over on the 'protected' sheet, then it is never picked up in the list that I paste into the 'pasted' sheet. The formula is exactly the same for all rows, and is as follows:

=IF(ISNA(MATCH(B2,Protected!a, 0)),"","protected")


Can anyone think why it is not working beyond this limit? If it helps I could attach the excel file, but I'm not sure what the rules are about attachments?

Thanks,
Nick

Is your protected range protected!a:a ? It is Protected!a in your example

Yes that worked perfectly thanks! It was a very small change but seems to have done the job.

Would you mind explaining what the difference is between protected!a:a and Protected!a please?

Thanks again

To be honest, all I know is that a range is always defined with a :.like a1:b4 or b:b,2:2, etc. I never heard of a range defined as you did
Maybe you could also try =if(countif(b2,Protected!a:a),"protected","") It might be faster