Yes sir, one common thing that is often missed is the Trading Flag on the Demat Connection itself.
Even if the Trading Flag is enabled inside the Group for both the Master and Child accounts, orders may still not be placed if the Trading Flag is disabled on the connected demat account.
Please verify the following:
-Trading Flag is enabled in the Group.
-Trading Flag is enabled for all Child accounts.
-Trading Flag is enabled on the connected Demat Account from the Demat Connect page.
-The broker account is connected properly and is active.

In many cases, enabling the Trading Flag from the Demat Connect section resolves the issue immediately.
If everything is enabled and the issue still persists, you can contact the support team for further assistance.