Can you tell us the exact criteria you used.

Hi James, "NOT" is for Yes/No fields.  For text or numeric fields, you need to use:

    MyField <> "IPR Support Unit"

Thanks guys!

I'll give that a try Kevin.

'Not' also works for text fields.

Depending on your query, as Kevin Robertson eluded to, if the referred to is relational you may need to specify that ID.  
If it isn't relational - Why isn't it?   You shouldn't be storing repeating data.

Hi Kevin, in the criteria box on the query design screen, if you type

   Not "IPR Support Unit"

the SQL screen will show the actual SQL statement, which will convert the above to:

   Not (MyField = "IPR Support Unit")

So the "Not" operator is still used for boolean expressions only, as it has always been the case.

The query designer lets you type "NOT 'text value'" merely to convenient the user.  It is not the actual SQL syntax.  Lots of expressions allowed by the query designer are not the actual legal SQL syntax (e.g. the criteria box lets you type >1 And <10, but the actual SQL syntax is field>1 And field<10).  The actual SQL statement shown on the SQL screen is the actual syntax, and it is what counts.