The Ethereum blockchain uses something called a smart contract. Smart contracts are different to normal transactions for a number of reasons, and therefore some wallets are unable to technically accept them.
If you send a smart contract to a wallet which cannot accept them, although the coins might be confirmed on the Ethereum blockchain, either the coins have no wallet to be accessed in, or the wallet provider will need to manually approve the transaction, which can be time consuming.
It is very important to check if your wallet can accept smart contracts or Ethereum (ETH) before sending coins.
To learn more about smart contracts, click here.