If you are using a high speed sander, you need a disc with a hole in the center, Self adhesive discs are for patternless DA sanders.
If you are trying to get them to stick to a DA pad, try cleaning the backing pad, and get all the remnants of old paper off. The vinyl cover needs to be smooth if you want self adhesive discs to stick at all. The tool sale discs you got probably need to have the sticky stuff reapplied, so follow Dinger's advice.
Don't put vinyl top adhesive on your DA backing pad, unless you want to replace it along with your sandpaper.
my signature lines...not really directed at anyone in particular..
BE different....ACT normal.
No one is completely useless..They can always be used as a bad example