When i attempt to type in in-game chat the screen goes black and spacebar doesn't work

When i type in minecarft pe, in the in-game chat, the screen goes black and the space bar doesn't work. I cannot talk to friends online, see what I'm typing and when i do type all the words are mashed together to form one big word. I cant sign in or register to mcpe servers. Also i have an app that gives me commands, and i need to use the spacebar to type the commands, so i cant do them. This is very frustrating and it is very difficult to play minecraft. I really want this to be fixed, so i can use these different in app function. Does anyone know what to ?
Thanks