The way bitcoin works is:

• The intended recipient has an account with a service or runs their own wallet software
• The intended recipient requests a bitcoin address from their account or wallet
• The intended recipent gives that address to the sender
• The sender has an account with a service or runs their own wallet software
• The sender has access to some amount of bitcoins at the service or in their wallet software
• The sender requests the service or wallet to create a transaction that pays an amount of bitcoins less than or equal to the amount the sender can access to the address that they received from the intended recipient
• The service or wallet to creates the requested transaction and broadcasts it to the network
• The transaction is eventually included in a block in the blockchain (confirmed) by a miner
• The intended recipient's service or wallet then has access to the bitcoins that were transferred with the transaction

So, there are only a few places where this could have gone wrong.

• 1. You (as intended recipient) didn't get the address from Kraken.
• 2. You (as intended recipient) did get the address from Kraken, but it became modified by malware after Kraken supplied it and before you gave it to the sender.
• 3. The sender didn't use the address that you gave him.
• 4. The sender thought he used the address that you gave him, but it became modified by malware after he received it and before he used it.
• 5. The sender's service (IR) failed to create and send the transaction that the sender requested.

That's it.

One of those things happened. All you need to do to understand what happened is figure out which one.

I suggest you go back through your communications with the sender and see what was requested.
I also suggest you and the sender both carefully check your computers for malware and malicious browser plug-ins.