我在一个窗口建了两个listbox控件单击其中一个触发一个事件但是在运行时必须两个都点击才触发事件，这是怎么回事？
Option Explicit
Private Sub Form_Load()
List1.AddItem "psi"
List1.AddItem "kPa"
List1.AddItem "MPa"
List1.AddItem "kgf/cm"
List2.AddItem "psi"
List2.AddItem "kPa"
List2.AddItem "MPa"
List2.AddItem "kgf/cm"
Text1.Text = Empty
End Sub
Private Sub List2_Click()
Dim x, y As Double
If Text1.Text = Empty Then
Text2.Text = Empty
ElseIf List1.Text = "psi" And List2.Text = "kPa" Then
x = Text1.Text
y = x * 6.895
Text2.Text = y
ElseIf List1.Text = "psi" And List2.Text = "MPa" Then
x = Text1.Text
y = x * 0.006895
Text2.Text = y
ElseIf List1.Text = "psi" And List2.Text = "kgf/cm" Then
x = Text1.Text
y = x * 0.0703
Text2.Text = y
End If
End Sub
