Tried with these (+ more which i do not have at hand right now) ->
COB LED 220-240v 7.5w (no name from a local store here -> c-light)
Osram ac03076 2700k 50/60hz 52mA 7w 220-240v
Osram ac32396 2700k 50/60hz 32mA 4w 220-240v
I tried them singular and all together. Same result.