I am currently using a samsung gusto 3 on a Verizon pay as you go plan,I would like to change over to my samsung convoy.I tried to do this on line several times .But I was unable to do so I get a message "unable to proceed at this time" I was told by the person that gave me this phone it has a good serial # and it was working good when taken out of service.....Why can't I activate it?