keyframe data lost on crtl+z

the pictures speak

i use this version

adobe edge animate cc 2015.0

when i want to cut and when i want to go back by crtl+z some keyframe value will lost can you help me please ?

this is my work

when i want to delete or cut it and i want them back i did here crtl+z

i deleted some keyframes by Del key

and when i did crtl+z

you see some keyframe got empty

thanks for helping me