You probably aren't sending to a segwit wallet address, in order for it to be a segwit transaction, you need to send to a wallet that starts with the number 3 (for example my segwit address is 352BZAx5w6Jabk5aYNpNLaqTYkLnorZDSN) also im not 100% sure but i believe you also have to send from your segwit wallet to. Meaning both parties have to have a segwit address.