Universal remote problem

I know this is not directly relevant to the topic of this group, but I 
bet someone here can help me.

I bought a One for All universal remote for my new home theater system. 
The remote works great for everything except my receiver, an Onkyo TX-
SR605. I have tried all the codes that One for All provides for Onkyo, 
but I can't get the on/off to work. Some codes let me turn the receiver 
on but not off, and others let me turn it off but not on. Any ideas?

TIA


-- 
Peter Aitken