Declined for a role due to being uncomfortable/awkward, help

[Makingplansfornigel1]

It was through an agency actually. I'm qualified as a teacher (apparently "outstanding") however I sometimes I wonder how.
Anyway I had a trial day as a HLTA/cover teacher in a nice primary school the other day.
I was with a year 2 class who were a bit rowdy, surely it's as I was a new face to them. Naturally I was a bit nervous/stressed but I tried to be friendly yet firm. I praised them but also employed the behaviour policy, using C1s/c2s, moving pupils, speaking to them about behaviour etc.
The 2 TAs also supported and guided, which was appreciated.
The headteacher didn't see me teach at any point, nor did any senior staff, only the 2 TAs.
They seemed friendly TAs telling me, oh you'll be fine here, it's a lovely school etc. And seemed supportive.
Anyway I had a phone call today from my agency telling me that they had decided not to take me on for the role as I had essentially seemed 'uncomfortable and awkward' with the children.
I presume the head decided this, however only the TAs saw me with the kids so I presume they fed back to the head.
I understand if they don't think I'm a good fit, however naturally disappointed as it was a really well-paying role. Luckily I have managed to get other work for at least next week.
I think the head or a member of SLT should have also observed me before making a decision, not just the TAs.

I was certainly a little nervous and the kids will naturally play up but I don't understand the uncomfortable/awkward thing.
I've had it before where I've been told I seemed 'nervous' even if I felt fairly relaxed.
Maybe I've just got a nervous disposition but I'm not sure what I can do about it.
The TAs were obviously trying to be friendly if not very genuine.
Anyway not sure what to make of this feedback and how to avoid it in future?

If the teacher has been told she seems ‘nervous’ in more than one setting, struggles to find long term teaching jobs, and can’t control a class of 7 year olds even when handing out several sanctions in one class, then the ‘underlings’ (who she admits she needed the support of) clearly have a point, don’t they?

And if you admit you’re nervous and stressed and have to move pupils/hand out warnings and sanctions, and speak to them about their behaviour, then you don’t sound like you have a good understanding of classroom behaviour management. So hard to blame the TA.