Sending a more than text on private message [HELP PLEASE]

Hello I am currently trying to use Photon Chat to send invites to other friends, which the player invites, when a room is made but I want to send more than text I want to send a instantiated game object which holds a image, a text object, and a button. I am using unity and it is an android project. Every time I run the game and that line of code: chatClient.SendPrivateMessage(StoresFriendsName, Instantiate(InviteSentPannel, InviteSentLocation)); runs it comes up with an error on the console which is NullReferenceException: Object reference not set to an instance of an object.

I want to be able to send this gameobject to the other player who is invited so they can accept or decline the game invite which is sent from the friend.

any help would be much much appreciated