主题：Excel 导出出现错误

导出excel文件时出现这个“指定的转换无效”，只要导出数字类型的就跳出这个错误，求解
此主题相关图片如下：转换无效.png

Dim ckl As WinForm.CheckedListBox = e.Form.Controls("CheckedListBox1")
Dim nms As New List(of String)
For i As Integer = 0 To ckl.Items.count - 1
    If ckl.GetItemChecked(i) Then
        nms.Add(ckl.Items(i))
    End If
Next
If nms.Count = 0 Then
    MessageBox.Show("至少要选择一列","提示",MessageBoxButtons.OK,MessageBoxIcon.Information)
    Return
End If

Dim dt As Table = Tables("评定计算_桩号明细")
Dim Book As New XLS.Book(ProjectPath & "Attachments\混凝土评定.xls")

Dim Sheet As XLS.Sheet = Book.Sheets(0)

For r As Integer = 0 To dt.Rows.Count - 1
    For i As Integer = 0 To nms.count -1
        Sheet(r + 5, i).Value = dt.rows(r)(nms(i))
    Next
Next

Book.Save("c:\reports\test.xls")
Dim Proc As New Process
Proc.File = "c:\reports\test.xls"
Proc.Start()

此主题相关图片如下：列表截图.png

勾选强度2 、强度3、强度值 就出错
此主题相关图片如下：模板截图.png