When you place your buy/sell order, they will be queue up waiting for buyer/seller to buy/sell your order.
This is because there are a lot more people placing orders before you.
Just be patient, it might take 1 hour, 1 day or even longer to buy/sell your altcoins.
That makes sense, but then ....... why don't I see your (or anyone elses) buy/sell orders?
Maybe because I do not have enough to match the size of your order?
Partial fills not possible?