Edit CommentService:

Add OffendingReport

Please For Work Craat Method Whene CommentTypeId=2 (1:Normal Comment , 2: OffendingReport):

Delete FK_TbComment_TbMessage1 with dbo.TbMessage.Id in RelationShips
fileds (MessageId,CommentTypeId,UserId,..) are nullable in Database
and when use reader should be check nullity first like this :
if(reader["CommentTypeId"] != DBNull.Value) 
        comment.CommentTypeId = Convert.ToInt32(reader["CommentTypeId"]);