Andrea Paints or Vallejo Paints

I had a thread earlier but may be some new people may want to add some thing. I re-order some paints from Andrea Minatures because the ones that came in the kit (the 9 bottle paint set/knight) were not mixing well and thought they might be old. Then I had some modelers advise me to bang against something hard to loosen but I still never heard or feel anything mixing inside the bottle. The new bottles I recieved, half were the same as the others. Some bottles I shake I can hear fluid swishing around where other I heard nothing and I have banged them against the concrete garage floor and still do not feel anything loosening up. All the paints I have used cover nicely. I wish to continue with these paints but I never know if they are mixing or not and some are really hard to sqeeze out of the bottle. Am I wasting my time with these or am I just a little slow at learning how they mix? I would appreciate any input. Soaking them in warm water does not do anything for these paints either. Any thing else to try before I throw them as far as they will fly? Thank you, frustrated painter!!!

Scott