急！！！出现错误"必须进行收缩转换才能调用可访问重载“ListItemCollection.Add”。

[sunnyshy]

刚发现程序出现了错误
Cmd.CommandText = "select distinct mvessel_cn AS '船名' from web_sa_query where ew='E' and vessel_op='" & clientcode & "' order by mvessel_cn"
Try
Cmd.Connection = websqlConn
websqlAdapter.SelectCommand = Cmd
If websqlConn.State <> ConnectionState.Open Then '数据库连接打开
websqlConn.Open()
End If
Cmd.ExecuteNonQuery()
If websqlConn.State = ConnectionState.Open Then '数据库连接关闭
websqlConn.Close()
End If
websqlAdapter.Fill(webDataSet, "table1")
myView = New DataView(webDataSet.Tables("table1"))

DropDownListGx.Items.Clear()
DropDownListGx.Items.Add("全部")
DropDownListGx.SelectedValue = "全部"
Dim i As Integer '干线船名添加列表项
For i = 0 To myView.Count - 1
DropDownListGx.Items.Add(myView.Item(i).Item("船名"))
Next
Catch ex As Exception
Dim shy As String
shy = ex.ToString
shy = ex.Message.ToString
Return False
End Try

执行到DropDownListGx.Items.Add(myView.Item(i).Item("船名"))时程序报错"必须进行收缩转换才能调用可访问重载“ListItemCollection.Add”。
DropDownListGx中则没有添加进任何内容

哪位大侠能帮帮我啊

[hackate]

Cmd.CommandText = "select distinct mvessel_cn AS 船名 from web_sa_query where ew='E' and vessel_op='" & clientcode & "' order by mvessel_cn"

看看

[sunnyshy]

我到数据库中查询结果为：

NULL
3242
3346
。
。
。
为什么上面会有一条空记录呢
正是因为出现这条空记录，程序才报错，怎样删除这个空记录啊？