Why won't this work?

I have a brick named Jim. I want Jim to switch to random colors. Example: green, (waits 1 second) red (waits 1 second) blue (wait 1 second). You should get the point. Here is the snippit

while true do jim.BrickColor.Random() wait(1) jim.BrickColor.Random() wait(1) end

Now, when I run it. It does nothing. Also I want Jim to go transparency for 2 seconds then back to normal. Example: Jim is in transparency .5, in 2 seconds he'll switch to transparency .0 and it will be a loop. Here is a snippit

jim=script.Parent while jim do jim.Transparency=.5 wait(2) jim.Transparency=0 wait(2) end

Any help?