alright guys, I just went to my car and get this fix
I found the reason which i couldn't push the white piece in all the way, in order for me to lock the glass piece
just in case someone have the same problem later on, so I will be putting on a little explain here:
inside the mirror housing, there is a module(or a motor whatever you want to call it) with wires connect to it
on that module there are 4 screws on the side and 1 in the middle
in order to push in the white plastic cover piece onto it, u have to loose the screw in the middle of the module
which comes out with a spring and a cylinder-shape white plastic piece, and of course the screw
after this step, u can start to push in the 2 plastic poles into 2 black rubber holes on the module
(make sure u center the medal arm inside the rubber holes first, otherwise u may break it and ur electric. mirror control won't work even tho you put the glass back in)
then you can have the center fit in, then screw back the cylinder-shape piece, the spring, and the screw
now the last thing u have to do is slide the mirrow piece back on the white cover piece, if u can't see weather it's lock in or not
u can always take a look from the bottom, and after that just push until u hear the "click" and u are done!
whoo~my mirror is fixed with $0 cost! B)