hi, i solve this issue,

 

solution is if you are creating you own custom class for DataManager  then you have to cast it when you are creating object.

 

following is the sample code.

 

TaxTrustMessanger.Components.TaxTrustDataManager objDataManager = (TaxTrustMessanger.Components.TaxTrustDataManager)CuteChat.ChatSystem.Instance.GetCurrentPortal().DataManager;

 

 

Regards

Gaurav