There could be a few reasons why your deposit was rejected:
The amount indicated on your proof of deposit doesn't match the amount you logged
Ensure the amount you input when you log the deposit matches the amount stated on your proof of deposit.
Your proof of deposit is invalid or lacks key information
To make sure your proof of deposit is valid, make sure it includes the following information: time and date of the transaction, total amount, and remarks if any.
If your deposit was sent to the wrong account number or the amounts don't match, this could also invalidate your deposit.
Your deposit check might have bounced
Ensure your checking account has sufficient funds before logging a check deposit to avoid issues.
Your deposit amount is a total of multiple separate checks
If you're trying to deposit multiple checks at once, make sure to create separate deposit logs for each check.
Check this article to know how to properly log your deposit.