Cannot trasfer file between Dolphin and Corsair thumb drive.

I’m using 11.3 x86-64 KDE4.4,I bought a Corsair 4GB thumb drive last week,but when I tred to transfer some file from Dolphin to Corsair,the ‘paste’ selection in pop up is grey color,it means I couldn’t paste thing into this thumb drive. I tried to modify the permission of this thumb drive,but failed,it pop up said I have no permission to do that.
What’s the problem?
And when I download a .rar file tried to extract it with Ark,it loading the archieve like never ending,what’s the problem?

You do not need to change permissions to a device like this.
Are you sure it’s not locked? Some devices have a small locking device…
Have you tried formatting it?

Nope,this is Corsair Flash Voyager,no lock option on it,and I can’t find any ‘format’ option for thumb drive in 11.3? How to format it?

You can use Yast > Partitioner or install Gparted from Packman

You must make sure the device is unmounted