Happened the same to me the first time that I made the practice trial (I'm someone that become easily nervous when under exam). Don't worry, I'm sure that the next time everything will be fine =)
Driving tests are just an exercise in "avoid all these instant fail conditions". I failed my Full G license by driving too slowly lol. Dunno why they bother grading these things. You either instantly failed or not lol. You'll get it next time dude!
I failed my first time too. But hey, I'm asian. I was guaranteed to fail anyways. Felt like Spongebob afterwards. Jokes aside, just don't let it get it to you. Plenty of people failed the drivers exam before and some failed multiple times but keep going. Just keep persevering.