"kenwood/yamaha" is a result produced by the obsolete internal decoder inside irtool.

The decodes you want (that come from decodeir.dll) should appear in a small pop up window before you see the decode in the main window (the obsolete decoder should only be called after you dismiss that pop up window).

The decodeir from RC is also obsolete, but not so obsolete that it should explain your problem. You should get decodeir.dll from hifi-remote.com

If you don't get the small pop up window, there are several possible reasons, some of which are:
1) You got the wrong version of IrTool (one that doesn't use decodeir.dll)
2) You didn't put decodeir.dll in a place irtool.exe can find it (but putting them both in the same folder ought to work). I assume you put decodeir.dll in that folder; you didn't just put the .zip containing it in that folder.
3) You are using Pronto Hex that your obsolete version of decodeir.dll doesn't understand.
4) You are using Pronto Hex that no version of decodeir.dll understands.