non constant radius with CreateTube function

Hi,

I want to create a tube with two kinks.  However the radius near the kinks is different to my defined radius in the CreateTube function.  I would expect a constant radius .Here is a playground example:

http://www.babylonjs-playground.com/#1EX6VF

Furthermore, if I reduce the distance between the kinks I get a strange effect:  

http://www.babylonjs-playground.com/#1EX6VF#6

I`m using BabylonJS version 2.4.

Thanks for your help