This is the skeleton file that I use. It works perfectly and I don't have any problems.
http://uploading.com/files/185fa4fc/Working%2BSkeleton%2Bfor%2Bmaya.mb/
The steps you have done is correct, but before you skin your mesh. Make sure that you delete the history in the mesh. (Edit >> Delete By Type >> History) Then you would continue on with the skinning and the steps after that. Then you shouldn't have a problem with the disappearing button.