I have recently gotten BitMinter on Linux, and was hoping to try GPU mining. However, as soon as BitMinter starts, it gives the following messages:

BitMinter Client v1.6.1 started
No OpenCl-compatible GPUs detected
Probing all ports for external devices
Probe failed: No serial ports found
No external devices detected.

If I then click the play button to run, then it tells me:
Error: null
scala.runtime.NonLocalReturnControl$mcV$sp

As well, the engine start button is not showing now, however the previous issues existed before this