cannot install new linux


I created a start up disk with Unetbootin and wrote RuneAudio_bbb_0.2-beta.img to my drive.
Insert the drive and power up while holding the boot switch for at least 20 seconds.
I do not see one of the leds flashing though.
If I power up without holding the switch the leds start flashing after 4 seconds

can anyone tell me what I’m doing wrong?