ERROR:  pg_atoi: error in "NULL": can't parse "NULL"

Hi , 


I have any column. 'test' . When I insert 'none' to column 'test' , no
problem.

test
-----
NONE 

But when I update column , postgreSQL return this error.
ERROR:  pg_atoi: error in "NULL": can't parse "NULL"

Where is problem ? 

Thanks
-- 
Rado Petrik <r.p@szm.sk>