The most common cause of this fault in the Bass Station Keyboard is that the MIDI RX (receive) and MIDI TX (transmit) channels have been set to different values. This causes the keyboard to be "Dead" (no sound). Here's how to fix this:

Turn the keyboard on.
Set the UTIL. MODE switch (below the PORTAMENTO knob) to the KEY'B position.
Press the TX KEY once (the second E up).
Press the lowest C key once (labelled 1).
Press the RX KEY once (the second F up).
Press the lowest C key once.
Now return the UTIL. MODE switch to the OFF position.
Playing the keyboard should now produce sounds.

Other possibilities include:

Volume knob set to zero
An incorrect MIDI RX channel has been selected when playing from another keyboard
A volume MIDI message of zero has been received
The mod wheel has been assigned to control volume - try pushing the mod wheel forward to see if volume increases