Multiple IF’s with ISERROR

Hi,

I currently use the following formula using IF and ISERROR i.e.

=IF(ISERROR(IF(O12-(O12/100*80)<S12,"",IF(O12="","","Warning 20% or less Cover Remains!")))," ",(IF(O12-(O12/100*80)<S12,"",IF(O12="","","Warning 20% or less Cover Remains!"))))

What I’m after is to add an addition condition e.g. using “IF(O12-(O12/100*80)<S12” and “IF(O12-(O12/100*90)<S12” which would display either Warning 20% or less Cover Remains! or Warning 10% or less Cover Remains! incorporating ISERROR to avoid #N/A

Any help would be greatly appreciated

Many thanks

Rob

Excel version 2003