First, try to plug the keyboard in another Usb port of your computer
Second, please try to replace the Usb cable by another one.
Third, try to reset the Keyboard by pressing '+' and '-' and power up you keyboard.
Fourth, Check if the keyboard is well sending Midi Data:
Please download: http://www.midiox.com/
1/ Open Midi-OX
2/ Click on "Option/Midi Devices..."
3/ In Midi Input, Select your Keyboard Click 'OK'
4/ Open the 'Main outPut Monitor'
5/ Reproduce the problem.
6/ Make sure that a midi signal is well send from your keyboard to the "monitor - Output" window.
7/ forward us a screenshot
Open the Midi Monitor Application.
1/ Reproduce the problem on the hardware
2/ go to : File/Save As...
3/ Send us the file