Could be incorrect jumper settings, IDE cable problems, or simply that things aren't connected properly. Best to verify all is well with your original drive and if it does, go back to step 1 and try again.

A few people have had some problems with an older verion of InstantCake on Series1 DirecTV units; the workaround seems to do the trick for them and the current version does not seem to cause any problems

A few others have had quirks relative to their specific PC brands, but of the program appears to be operating with out errors, its most likely to be a drive compatiblity issue or a jumper/connectivity issue... search around on the forum, you'll find others who have had similar issues and how they ultimately solved the problem.

For answers to commonly asked questions, please refer to the
InstantCake Instructions and Release Notes,
Official InstantCake Discussion Thread, and the
Official PTVnet Discussion Thread