Can't compare string and float values error message

Hello,

I am receiving the error message above when trying to use the formula below.  Any assistance would be greatly appreciated.

if [Manager Call Monitoring]<.80 THEN 'Does Not Meet'

ELSEIF[Manager Call Monitoring]<=.8999 THEN 'Meets Some'

ELSEIF [Manager Call Monitoring]<=.9799 THEN 'Meets All'

ELSEIF [Manager Call Monitoring]<=.9999 THEN 'Exceeds'

Elseif [Manager Call Monitoring]>.9999 THEN 'Sig Exceeds'

ELSE 'NA'

END