If this was a listening exercise then you were expected to wwrite the Greek. If it was a translation then "Nice try" is correct as you can see from the top of this page.
In other words, we cannot see what kind of exercise you had nor what you wrote. When a sentence is rejected you should use the Report option at the bottom of the exercise page.
Here's how to report.
Go to the bottom of the exercise page where you'll see REPORT Click on that:
Then choose what you want to REPORT: (You'll see these to choose from.)
-The audio does not sound correct.
-The dictionary hints on hover are wrong or missing.
-The Greek sentence is unnatural or has an error.
-The "Correct solution" is unnatural or has an error.
-My answer should be accepted. This is the one you should click on if your translation was not accepted.
After choosing the REPORT you want to make you should post on the comment page.