Keiki question

I posted this question on the other forum but didn't get answer yet.
Maybe you guys would know:

Four of my plants started to grow keikis on the old spikes recently.
First it was just pulchra and lueddemanniana which are prone to producing keikis, so I didn't worry and was actually happy.
Then it was a hybrid - Phal. Coral Isles x corningiana.
Now it is Phal. cornu-cervi - on both spikes:



What am I doing wrong? Could it be wrong type of fertilizer? I use dilluted 20-20-20.
Thanks a lot.