Hi Ckyuk

I'm no expert but try this and let us know if it works:-

1> Give some thickness to the object if it doesn't already have one and make sure the normals are facing outwards.

2> Give the objects mia_material and from the attribute editor select preset>glassthick>replace

3> In your render settings, keep reflection & refraction at 5 and a max trace depth of 10.

4> Increase your ray depth limit for all of your lights under raytracing shadows to 5 as well.

Render and post the results.