این شاید بهتر باشه

Private Sub Command1_Click()
n = Val(Text1)
Select Case n
Case Is > 0:
Label1 = " positive"
Case Is < 0:
Label1 = "negative"
Case Else:
Label1 = "Zero"
End Select
End Sub

Private Sub Form_Load()
Text1.Text = ""
Label1.Caption = ""
Label1.AutoSize = True
End Sub