Could someone suggest what did I do wrong?
You're probably hashing a string and not a hex. On the third step, you'll have to hash it as a hex and not as a string. Based on the wiki's example if you hash the corresponding public key as a hex you'll get the correct result:
0b7c28c9b7290c98d7438e70b3d3f7c848fbd7d1dc194ff83f4f7cc9b1378e98
But if you hash it as a string you'll get a different result, which is:
a9ce83de3a0ff3516b7c50cdd787e9f69f152f227d93c9512774231e7132e925
You can hash a hex through
emn178.github.io. Just choose "hex" instead of "text" in the input type dropdown. Same thing must happen on RIPEMD-160.