标题：显示数据类型错误，但不知道怎么纠正

   Dim s1,s2,s3,sum1 As double
    s1 = DataTables("期初库存").Compute("Sum(重量)","[克重] = " & e.DataRow("克重")   and "[编号] = '" & e.DataRow("编号") & "'" and "[幅宽] = " & e.DataRow("幅宽"))
    s2 = DataTables("生产清单").Compute("Sum(重量)","[克重] = " & e.DataRow("克重")   and "[编号] = '" & e.DataRow("编号") & "'" and "[幅宽] = " & e.DataRow("幅宽"))
    s3 = DataTables("发货清单").Compute("Sum(重量)","[克重] = " & e.DataRow("克重")   and "[编号] = '" & e.DataRow("编号") & "'" and "[幅宽] = " & e.DataRow("幅宽"))
    sum1=s1+s2-s3
    e.Datarow("重量") =Sum1


库存表的一个计算公式，“克重”列改变时弹出窗口说 字符串 到long 转换无效，不知道代码哪里需要改动，谢谢。

Dim s1,s2,s3 As double
Dim dr As DataRow = e.DataRow
Dim s As String = "[克重]  = " & dr("克重") & " And [编号] = '" & dr("编号") & "' And [幅宽] = " & dr("幅宽")
s1 = DataTables("期初库存").Compute("Sum(重量)",s)
s2 = DataTables("生产清单").Compute("Sum(重量)",s)
s3 = DataTables("发货清单").Compute("Sum(重量)",s)
dr("重量") = s1+s2-s3