Java.lang.IllegalArgumentException: cannot accept class com.veersoft.gwt.shared.trailbalance.TrailBalanceClassResult as memcache object

To make my application faster, I use MemcacheService. Now when I try to put the object in MemcacheService, I get the following error:

java.lang.IllegalArgumentException: can't accept class com.veersoft.gwt.shared.trailbalance.TrailBalanceClassResult as a memcache entity.

Entity Details:

• This is a regular Bean that implements the IsSerializable interface.
• This is not a dataStore object. I use this only for rendering from the browser side (i.e., the Delayed task will calculate the results and send these results to the browser).