First, check the symbol you are trying to trade and any error message displayed.
The following may prevent a trade from being opened:
Market status: Check that the instrument is within its trading hours. Weekends, public holidays, market closures or temporary trading suspensions may affect availability.
Account status: Make sure your account is active and there are no trading limitations affecting your ability to trade. If you have received an email from Axi about an account-related action or trading limitation, check your inbox and spam/junk folder.
Funds or margin: Make sure you have sufficient available funds and margin to open the trade.
Product availability: Check that the symbol is available for your account type and that there are no product-specific limitations affecting it.
If you still cannot open the trade, provide a screenshot of the error, the symbol, the attempted trade details and the approximate time of the attempt for further investigation.