主题：这组代码错误何在？请不吝赐教

Dim Nu As String=CurrentTable.Current("编号")
Dim cm1 As WinForm.ComboBox = e.Form.Controls("ComboBox1")
Dim drs As List(Of DataRow)
drs = DataTables("长期医嘱").Select("[编号] >='Nu'")
For Each dr As DataRow In drs
    dr("住院号") = cm1
Next

[编号] 为字符型，ComboBox1为窗口住院号列表项目框，目的：将“编号”大于当前行“编号”的住院号统一设置为ComboBox1中选择的“住院号”。