reconnected the transmitter to the RFToy and verified that it works.
So, it looks like there is an issue with my OSPi.
Hardware:
OSPi controller version 1.4
Two extension modules
Raspberry Pi 2 model B
Two Netgear Powerline 500 ethernet adapters
Software:
Noobs version 1.4.0
OSPi firmware version 2.1.3