Error #2173 when sending Gravity message

Question

I have a problem with Map objects, while using Gravity. All messages works ok, except the ones which includes Map objects. They throw the following exception:

ArgumentError: Error #2173: Could not read the object in the stream. though Class:org.granite.collections.BasicMap do not implement flash.utils.IExternalizable,but we know that it's Class:externalizable by its alias.

I've found that this error occurs when you do not include granite-essentials.swc, but I don't think that's the case, because normal messaging using RemoteObject works fine, even with Map objects.
Any help will be appreciated.

Answer 1

The problem been solved by adding the following line into my GravityManager class: registerClassAlias("org.granite.collections.BasicMap", BasicMap); I hope it will be useful for someone.