Rounded corner effect, changes shape on resize?

Question

I'm using Illustrator CS5 on OSX. I run into this strange behavior and I can't figure out why it happens (and stop it from happening).

This is what I do:

1. Draw a rectangle
2. Effect > Warp > Arc
3. Set to -6
4. OK
5. Effect > Stylize > Round corners
6. Set to 6px
7. OK

Then, I take the corner (shift pressed) and resize the shape, making it smaller. Then at a certain point the shapes deforms.

Answer 1

Make sure you have Scale Stroke & Effects On. This will help scale any effects or styles you have placed on an object when changing the size of said object. Just Double-Click the Scale Tool and the box should be down below. Just check it and that should do it.

Answer 2

just turn on 'scale corners' in the transform palette, done