ABS Issue

i wanted to bleed my brake system on octavia Mk1 20007 and surprised that the rear left wheel doesn't get oil from the ABS Unit and even when i followed the line to the ABS unit, it doesn't.

is it now an ABS issue or the wheel sensor?

P.S.the two lines from the main master are giving oil to the ABS.

Thanx in advance for any help or advice!!