Can't synchro summon?

[Zorkk]

I'm new to this game, and I just got my first Synchro card. Tutorial showing me how to summon them popped up, great. Only issue is, when I take all the steps I'm told I need to summon a Synchro card, in an actual battle, it won't let me. My guess is I've done something wrong, but no idea what. I'm trying to synchro summon Ally of Justice Field Marshall (level 9) using Feral Imp (level 4), Dragonic Guard (level 4), and Kagemusha of the Six Samurai (level 2, and the Tuner). All three are on the field, and I haven't summoned anything else this turn. What's going on?

[droplet]

synchro summoning doesn't work like ritual summoning where the level requirement can be more than what it asks for, the levels need to be exact i.e. to summon a level 9 synchro monster the materials must be exactly 9.
since ally of justice field marshal is level 9 and the materials you would use add up to exactly 10, you wouldn't be able to summon it, whereas if you had ally of justice decisive armor (synchro level 10) in your extra deck you would be able to summon that

[minimum]

exact amount of level requiered + exact type of tuner or monster(s) = synchro is fast but has its restrictions like anything in this game ^^

[Zorkk]

Ahh, ok. Thanks!