How to properly render refractive/transparent materials in Catia V5R16

I am struggling to get a proper effect out of my rendering process. The software is very old, so perhaps some effects are not even possible but it couldn't harm to ask.

I am trying to render an assembly which consist of glass tubes. The glass material however, does not render properly. It supposed to be transparent and refractive but instead, the background colour diffuses all over the part and all I get is almost solid coloured part.

I gave it a go on a modern 3D software and - to no surprise - everything looked just fine.

I've tried different material settings but the effect stays the same. Any ideas?