主题：combox的过滤条件问题

Dim auditopinions As List(Of String)
For m As Integer = 0 To strsn.Length - 1
    auditopinions = DataTables("audit").GetValues("auditopinion"," sn= '" & strsn(m) & "'","auditdate desc")
    
For Each ap As String In auditopinions
    Output.Show(ap)
 MessageBox.Show(ap)
Next

Next

If auditopinions.Contains("") = False Then
    MessageBox.Show("已经审核的数据不允许重新审核,请重新选择.", "提示",  MessageBoxButtons.OK ,MessageBoxIcon.Information)
    Return
End If

为什么这个代码不管auditopinions是不是包含空，都是弹出提示框？注：MessageBox.Show(ap)明明是空白。