A few different things can cause a trade rejection. We’ll start with the small stuff.
Do you have $$ in your account?
Do you have any pending orders? Pending orders affect your buying power and therefore can cause subsequent/additional orders to not go through.
Is the stock market open? Standard hours are M - F from 9:30AM - 4:00PM EST
Do you have any Cash Account Violations?
Is your account restricted?
If you've checked all of those and still aren't sure, please reach out to us on the app’s Live Chat or via email at firstname.lastname@example.org!