SoC for a Ranger/monk

I recently accuired the SoC and when I found a boss to use it on, it says I can't capture the skill, cuz its a different skill type or something llike that anyways, any1 know of a boss that will work for a Ranger/Monk to use SoC
thx in advance

You need to find a ranger boss. You can only capture elites from your character class. There is a list of elite bosses in forums somewhere. A search will turn it up.

You could also find a monk boss. You can identify these because the monk has a blue aura, while the ranger has a light green one (not to be confused with a necromancer's dark green).

I think there are some that randomly spawn around Lion's Arch, if you go exploring.