From my understanding, you simply need to use a SHA256 function to hash the block's header (Block hash and merkle root) then add the nonce at the end like this article explains.
However, I can't manage to get the correct next block hash. By using the block #505400 :
Hash : 00000000000000000023b89dd18f6be5a6c03a71cd864ccbdf024683114b9ce3
Merkle root : a3defcaa713d267eacab786c4cc9c0df895d8ac02066df6c84c7aec437ae17ae
Nonce : 2816816696
Next block hash : 0000000000000000007625ff74171cf53e301c3e5013bf2184e2629a2da0fc8d
What I am expecting : sha256(Hash + Merkle Root + Nonce) = Next Block Hash
However I get this :
What did I do wrong?