I am following a tutorial and I have rounded a sharp corner made by the pen tool with effect>stylize>round corners. I am using this option as the direct selection round corner option is not possible for CS6. I am not really happy with the result though it doesnt round it as much as in the tutorial. This is my attempt...
Also when I upped the radius it didn't increase the roundedness.
And this is the example in the tutorial...
While it's nice to be able to use automatic rounding (Live Corners) available in the later CC versions of Illustrator, it's entirely possible to recreate nice curves manually with just the Pen tool. The rounded corner effect in CS6 is not really up to the job TBH.
Example. This was made in Illustrator CC, but I just made the curve manually with the Pen tool. This is also possible in CS6.
If you have little experience with the Pen Tool, the Bézier Game is excellent for learning how to use it efficiently.
That "tutorial image" is not using the round corners effect.
The round corner effect has a limit, you can see that in your image. There's no way to overcome the limit without altering the underlying angle. If you increase the angle of the joint, the rounding will be smoother. The effect will only round so far and can often be sort of oblong for some joint angles.
The curve in your second image has either been manually created, or created via a corner rounding tool such as Live Corners in newer AI versions or the Dynamic Corners from VectorScribe plugin. It is absolutely not created via the Round Corners effect.
