Initially delete button is disabled in flight reservation window

SystemUtil.Run "C:\Program Files (x86)\HP\QuickTest Professional\samples\flight\app\flight4a"
Dialog("Login").WinEdit("Agent Name:").Set "sabeer"
Dialog("Login").WinEdit("Agent Name:").Type  micTab
Dialog("Login").WinEdit("Password:").SetSecure "510737345f6c4de59ea286706d40499b4428a037"
Dialog("Login").WinButton("OK").Click
Window("Flight Reservation").WinButton("Button_3").Check CheckPoint("Button_3")
Window("Flight Reservation").Close