Normally, there should only be a single audio interface (soundcard) used with a computer, and when using ASIO sound drivers for low latency audio I/O, there is an ASIO limitation that you can ONLY use one driver at a time with your DAW, the problem is that you're using two interfaces at the same time, the Windows OS is using the Yamaha, and Mixcraft is using the 11 rack, there are at least a few different options here...
1) Disconnect the Yamaha unit from the computer, then hook up your monitor speakers to the 11 rack's main outputs, then go to windows sounds and setup windows to use the 11 rack as it's default audio device.
2) Disconnect the 11 rack's USB connection to the computer, and hook up the 11 rack's main analog outputs to the Yamaha's stereo line inputs, then setup Mixcraft to use just the Yamaha for it's audio I/O (input/output).
3) Connect your nice monitor speakers to the 11 rack's main outputs, then use the 11 rack ASIO drivers as your only audio interface for Mixcraft, and get some less expensive speakers for the Yamaha and leave that setup for Windows to use for normal non recording purposes.
4) Leave the setup as it is, use the 11 rack with Mixcraft for recording with headphones, and when you are not actively recording go into Mixcraft's settings and change the audio I/O device to be the Yamaha for playback through your monitors.