主题：在表中输入数据时，出现如下错误提示，求解

.NET Framework 版本：2.0.50727.1891

Foxtable 版本：2012.11.29.1

错误所在事件：

详细错误信息：

System.NullReferenceException: Object reference not set to an instance of an object.

   at System.Data.NameNode.Eval(DataRow row, DataRowVersion version)

   at System.Data.BinaryNode.EvalBinaryOp(Int32 op, ExpressionNode left, ExpressionNode right, DataRow row, DataRowVersion version, Int32[] recordNos)

   at System.Data.BinaryNode.Eval(DataRow row, DataRowVersion version)

   at System.Data.DataExpression.Invoke(DataRow row, DataRowVersion version)

   at System.Data.Index.AcceptRecord(Int32 record, IFilter filter)

   at System.Data.Index.ApplyChangeAction(Int32 record, Int32 action, Int32 changeRecord)

   at System.Data.DataTable.RecordStateChanged(Int32 record1, DataViewRowState oldState1, DataViewRowState newState1, Int32 record2, DataViewRowState oldState2, DataViewRowState newState2)

   at System.Data.DataTable.SetNewRecordWorker(DataRow row, Int32 proposedRecord, DataRowAction action, Boolean isInMerge, Int32 position, Boolean fireEvent, Exception& deferredException)

   at System.Data.DataTable.InsertRow(DataRow row, Int32 proposedID, Int32 pos, Boolean fireEvent)

   at System.Data.DataRowCollection.Add(DataRow row)

   at Foxtable.RowCollection.method_1()