Access - Why does (Nbr) work but not (Per Nbr) in query

I am running an alter table query to add a primary key:

Alter table 2
Add primary key (Nbr);

When the ID is just (Nbr) this works - but not when it is (Per Nbr). In the latter, i get the error in Constraint.

Thank you
exp vgAsked:
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is "Per Nbr" a single column? If so, try enclosing it in brackets:
...key([Per Nbr])

If it is two columns, then try putting a comma between the field names:
...key([Per], [Nbr])

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It is best to avoid spaces and special characters in names.
exp vgAuthor Commented:
This is how the data come downloaded, so I do not want to modify it.

Thank you.
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Microsoft Access

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