Excel IF(OR) - two OR's formula works but three doesn't?

I can get a two possibility formula to work but not a three. I thought it would just be adding a comma for another term then adding a comma for a value. Please can anyone tell me why its not working?

Working one:

=IF(OR(C6="buy", C6="hold"),(F5*(D6+1)),(E5*(D6+1)))

Not Working:

=IF(OR(C6="buy", C6="hold", c6="sell"),(F5*(D6+1)),(E5*(D6+1)),0)