Make sure that you are using the latest software and firmware versions.
Make sure your device is listed in Network View as connected and online (Green ON indicator).
Check the name of the DSP block in the device. It is very important that the name of the DSP block in the design file matches exactly with the unit in Network view, otherwise you will not be able to load the design to the physical device. The name can be changed either in the design file or the DSP units name can be changed in Network View, right click the device to "Device Setup".