>Thank You for advise, Edward.
>
>There is only one primary key in that table, it determines by one field,
>and I've tried to remove this tag already.
>
>Do You know what more reasons for this error can be?

I don't know if some rules/defaults/triggers fire during PACK, but you can try to remove them too. If it's still unsuccessful...
togda wy mozhete s chistoy sovest'yu steret' etu table.