I have set it up as it was shown below and do not have any traffic going over my low priority class-

class htb 1:30 root leaf 30: prio 3 rate 120Kbit ceil 480Kbit burst 6Kb cburst 2213b
Sent 0 bytes 0 pkts (dropped 0, overlimits 0)
lended: 0 borrowed: 0 giants: 0
tokens: 327680 ctokens: 29519

Any idea why?

at the same time-

class htb 1:10 root leaf 10: prio 1 rate 240Kbit ceil 600Kbit burst 6Kb cburst 2367b
Sent 16868735 bytes 78519 pkts (dropped 0, overlimits 0)
rate 2984bps 17pps
lended: 78519 borrowed: 0 giants: 0
tokens: 162561 ctokens: 24746

class htb 1:20 root leaf 20: prio 2 rate 240Kbit ceil 600Kbit burst 6Kb cburst 2367b
Sent 187917149 bytes 194261 pkts (dropped 32273, overlimits 0)
rate 30835bps 34pps backlog 108p
lended: 194153 borrowed: 0 giants: 0
tokens: -31678 ctokens: 10837