Python: no if in second loop [duplicate]

This question already has an answer here:

• Python rounding error with float numbers 2 answers

Im not sure if Im nuts or something, but look at this code:

a=1
while a<=2.2:
    if a==1.4:
        print "OK"
    a=a+0.4

output: "OK"

changed condition to 1.8:

a=1
while a<=2.2:
    if a==1.8:
        print "OK"
    a=a+0.4

output: nothing!?

Can anyone help me here?