I am a beginner in writing smart contract. I want to deploy a crowdsale and token contract on the Kovan testnet. Everything works well except when I tried to send KTH to the crowdsale contract. I always get "reverted transaction" in the end. Could someone help me solve this situation? I am using the standard Crowdsale and Token sale contract from openZeppelin and truffle suite.
Crowdsale contract: https://kovan.etherscan.io/address/0x68321f1380ac45be3f3d85d0cd95d1ac5710b8a9#code
Token contract: https://kovan.etherscan.io/address/0xb76b6ae76cee43e0b32588ffc112efca3c781f1e#code