levels of nesting

hi i am trying to get this formula to work in excel 2010 :

=IF(AO39>5500000, 350,IF(AO39>4800000, 300,IF(AO39>4000000, 250,IF(AO39>3200000, 200,IF(AO39>2400000, 160,IF(AO39>2000000, 130,IF(AO39>1500000, 100,IF(AO39>1250000, 80,IF(AO39>720000, 40,IF(AO39>400000, 20,IF(AO39>170000, 10,IF(AO39>60000, 2,))))))))))))

but i get this message:

the specified formula cannot be entered because it uses more levels of nesting than allowed in the current file format.

Can some one help please

thanks a lot it work a treat