I don't think the 3000 supports alpha channel (1%) transparency. I think the image has to be 1 of 16 colors grayscale and you have to select the color you want to be transparent. If you would like, email me your config at the addy on my profile and I will have a look.

And, next question. Are you trying to add buttons on the 'Devices' or 'Pages' page? If so, this could be your issue. The 'default' buttons may be coming up in front of your own. Your config will allow me to see what is happening as to try and diagnose here is not profitable.