forcing roots on old canes or pseudobulbs

[daddydoall]

Any suggestions on sparking fresh roots on old relatively spent growths? I have gotten some very cheap divisions from SBOE but have had many refuse to produce new roots even off the single "new-good" cane that is forming in spite bottom heat and even moisture. It is amazing how they look alive for so long with out roots!

Of course I can buy bigger healthier specimens but still one must try!

I recently tried rooting hormone but it did not seem to do the trick.