open system form by click on button

hi .......................open system form by click on button ......... i have created a button .. when i want to click on button another form will not display.....

this code we are used but its not working ....... plz help me..............

even messagebox not display here.....

Private Sub SBO_Application_ItemEvent(ByVal FormUID As String, ByRef pVal As SAPbouiCOM.ItemEvent, ByRef BubbleEvent As Boolean) Handles SBO_Application.ItemEvent

If ((pVal.FormType = 139 And pVal.EventType <> SAPbouiCOM.BoEventTypes.et_FORM_UNLOAD) And (pVal.Before_Action = True)) Then

'// get the event sending form

oOrderForm = SBO_Application.Forms.GetFormByTypeAndCount(pVal.FormType, pVal.FormTypeCount)

addbutton()

End If

If (pVal.FormType = 139 And pVal.ItemUID = "1001") Then

If pVal.EventType = SAPbouiCOM.BoEventTypes.et_ITEM_PRESSED Then

SBO_Application.MessageBox("Hi")

End If

End If

End Sub