I'm getting a DuplicateKeyException error in my C# code. I've set Auto Generated = true, and Auto-Sync = OnInsert in my dbml. I'm not even touching the PK field in any manually written code (as seen below [My primary key field is actually called PK]). using (DeviceExerciseDataDataContext context = new DeviceExerciseDataDataContext()) { foreach(Data tgudData in data.Data) { tgd = new tableData(); tgd.FK = key; tgd.Time = tgudData.TimeStamp; tgd.Calories = Convert.ToInt32(tgudData.Calories); tgd.HeartRate = tgudData.AvgHr; tgd.BenchAngle = tgudData.Angle; tgd.WorkoutTarget = 0; tgd.Reps = tgudData.Reps; context.tableDatas.InsertOnSubmit(tgd); } context.SubmitChanges(); } This is the code for the column in the designer (columns are named PK and FK) [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_PK", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL", IsPrimaryKey=true, IsDbGenerated=true)] public int PK { get { return this._PK; } set { if ((this._PK != value)) { this.OnPKChanging(value); this.SendPropertyChanging(); this._PK = value; this.SendPropertyChanged("PK"); this.OnPKChanged(); } } } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_FK", DbType="Int")] public System.Nullable<int> FK { get { return this._FK; } set { if ((this._FK != value)) { this.OnFKChanging(value); this.SendPropertyChanging(); this._FK = value; this.SendPropertyChanged("FK"); this.OnFKChanged(); } } }