Grasshopper Boxes give me VB Rendering module error

I have 23800 boxes in my project that were made in Grasshopper - ' Center Box'. They worked fine and baked fine too, till I wanted to make a short animation with a VB module. I downloaded the module from this forum and it is named 'renderanimation.ghx'. 

When I tried to render actual scene the module gives me this error:

Unable to cast object of type 'Grasshopper,Kernel.Types.GH_Box' to type 'RMA.OpenNURBS.IOnBRep' 

All I can guess is that the error is related to object type, because I had some cylinders and rendering them went fine when I excluded boxes to find out what's wrong. Do I have to use different kind of boxes for the module? 

Any input would be greatly appreciated.

Hyo