运行时错误“91”，对象变量或with块变量未设置

大佬们求解：调试的时候 Set rngNum = rngNum.EntireColumn.Find(strS)显示”运行时错误“91”，对象变量或with块变量未设置“

代码如下：
Option Explicit
Public frmStatus As String
Public rowNum As Integer

Sub 查询员工信息()
     Dim strS As String
     Dim intRow As Integer
     Dim rngNum As Range, rngName As Range

     strS = InputBox("请输入员工的编号或姓名", "员工查询")
     If strS <> "" Then
         Set rngNum = Sheets("员工个人信息表").UsedRange.Find("编号")
         Set rngName = Sheets("员工个人信息表").UsedRange.Find("姓名")
         
         If rngNum Is Nothing Or rngName Is Nothing Then
              MsgBox "员工个人信息表错误，无法进行操作"
              Exit Sub
         End If
         
         intRow = -1
         Set rngNum = rngNum.EntireColumn.Find(strS)
         
         If rngNum Is Nothing Then
             Set rngName = rngName.EntireColumn.Find(strS)
             If Not (rngName Is Nothing) Then
                 intRow = rngName.Row
             End If
         Else
             intRow = rngNum.Row
         End If
            
         If intRow > 0 Then
            frmStatus = "查询"
            rowNum = intRow
            Load UserForm1
            UserForm1.Show
         Else
            MsgBox "没找到与“" & strS & "”相关数据!", , "提示"
         End If
    End If
   
End Sub