OH2 cannot handle iffft command

I’ve created a rule in Paper UI to play a soundfile when the specific item receives a command (ON). It works fine whe the rule will be started and from Paper UI.
Additional i created an iffft-apllet to send the command “ON” to work with this rule. It looks like, the openhab receives the command, but i always get a log-entry (openhab.log) that the command should be invalid…

2017-11-01 12:04:00.665 [WARN ] [o.openhabcloud.internal.CloudService] - Received invalid command ‘ON’ for item ‘GoogleHomeWZ_Control’

There are no entries in the events.log

Anyone any idea?