Error can't dump anonymous class Class (apatana studio)

The system has a mainDocument model with different subclasses for different types of documents.
With the code below, if I attempt to create a Document, it works fine, but
if I attempt to use one of the subclasses, I get the error:

can't dump anonymous class Class

With an Application Trace of:

C:/Ruby/lib/ruby/1.8/yaml/rubytypes.rb:6:in `to_yaml'

When i started using aptana studio (radrails) 1.1.6 etc.. i got this error.

I searched all over the net for rails or ruby error list for this kind.. i could not find this problem any where.

But it solved when stopped apatana from dubugging mode to regular mode.

I dont know why but it works me fine afterwards.


please put your comments if u find any other soultion