Why am I not allowed to send on Coinbase?

I'm really puzzled here. I've been trying to send some of my cryptocurrencies from my Coinbase account, but it's just not working. I've checked my balance, and the funds are definitely there. I've double-checked the recipient's address, and it's correct. So why am I not allowed to send? Is it a technical glitch? Or is there some sort of restriction or limit that I'm not aware of? I've been using Coinbase for a while and haven't encountered this issue before. Could you please help me understand what's going on? I'm really eager to get this transaction done.