POE mikrotik + planet

Hello.
I use Planet IPOE-E174(1 Ultra PoE - to - 4 PoE Gigabit Extender). via this device I powered 2 HP 8-port PD switch, KIRK400 and I try to powered mikrotik cAP-2n. because Planet support only POE method A, AP don’t receive power from it.
to fix this problem I connect it through RBPOE-CON-HP. but RBPOE don’t work with extender. just converter’s power led
flash every ~3.7 second.
If I connect converter to PoE+ injector (Phinong POE36U-1AT-R) it work fine.
Why is this happening and what can be done in this situation?