You might be unable to trade a stock on a particular exchange due to the following reasons:
Liquidity Issues:There may be very few or no buyers or sellers on that exchange, resulting in low trading activity and difficulty in completing your order.
Exchange Restrictions: The stock may not be listed or enabled for trading on that exchange due to regulatory or exchange-specific decisions.
Temporary Suspension: Trading for the stock might be temporarily suspended due to regulatory actions, corporate decisions, or pending announcements.