Are you just using a plian bucket or does it have an aerator?

Use an aerator.
Don't put too many in and overcrowd it.

i am useing a plain minnow bucket no aerator i know this would keep them alive longer but i buy them in the morning and most of the time before i get to the dock 15 min. away half are dead

You gotta have an aerator. At least until you get where you're going. If it's a two piece, flow through minnow bucket you can hang it over the side of your boat or off the bank, but I'd still use an aerator if you can. If it's not a flow through you gotta use an aerator and change out about half of the water every half hour or so. I've kept them alive for several days with a flow through hanging in the water.

Fill a 16oz. plastic Coke bottle with water, freeze it with the cap off. When it's frozen put the cap on and put it in the bucket with the shiners. Take it out after the water in the bucket chills down, but keep it handy and put it back in every now and then to keep the water cold.

We call them larsh some people call them cocahoe minnows just like we call a crappie a sac-a-lait depends on where you live I guess.

Like huckleberry said , keep them cold . We rarely use live minnows anymore but when we do we put the bucket inside an ice chest and pack ice around the bucket , if it's hot summer . The minnows will die of old age if you keep ice on them .