Question

why does the normal ball point or ink pen not work in space?

Answer 1

However,  a normal ballpoint pen won't work so well in the absence of appreciable gravity for the same reason that a normal ballpoint pen won't write upside down... the ink doesn't flow onto the ball in enough quantity for the pen to work.  

However there are several pens which are available which will write in any position.   My understanding is that these pressurize the ink to overcome either a lack of gravity,  or gravity pulling the ink in the wrong direction.

Answer 2

because the normal ball point or ink pen works on the gravitation force the get ink in the nip and in the space there is no gravity so the normal ball point or ink pen not works in the space