It worked perfectly for me ....any reason you have not copied the code verbatim?

Re LED1 never lighting, what happens if you comment out the random aspect & simple make mybyte = 1 (where 1 is the LED you're not seeing lighting up etc)...this should light the suspect LED up all the time & proves both the wiring/LED at least.

Re the same LED lighting in succession, I'd approach this by getting some debug/hserout info of 'mybyte' onscreen....else you're grasping in the dark. (no pun intended!)