one to many throw Batch update returned unexpected row count from update

[yuzhaoMR]

//table CustomerArchives
public virtual IList Evaluations { get; protected set; }
// Relationships
HasMany(x => x.Evaluations).Inverse().Cascade.All();

//table Evaluation
public virtual CustomerArchives CustomerArchives { get; protected set; }
// Relationships
References(x => x.CustomerArchives);

I think there is no problem I wrote.but throw exception "Batch update returned unexpected row count from update".
please help me