主题：case语句问题

以下代码通过函数取得s多字符串，其格式为： “A”，“B”

当判断值为A时，为啥不起作用？

'table权限统一设置
Dim s As String =Functions.Execute("获取所有已设置表名")
MessageBox.Show(s)
For Each t As Table In Tables
    Dim tname  As String = t.Name
    Select Case tname
        Case s
            t.Visible = False
            If user.Type = UserTypeEnum.User
                t.AllowEdit = False
            Else
                t.AllowEdit = True
            End If
        Case Else
            If user.Type = UserTypeEnum.User
                t.Visible = False
                t.AllowEdit = False
            Else
                t.Visible = True
                t.AllowEdit = True
            End If
    End Select
Next