66@Asish, you forgot to take into account the force of gravity.
A note on FBD's:
1) The first thing you must decide is the system for which you are supposed to draw the FBD and show this system separately removing all decorations.
2) The next thing to do is to specify a reference frame (I said reference frame and not a coordinate system)
3) Show all the forces acting ON the system (not the ones exerted by the system). For this purpose it may be useful to categorize the forces as long range and contact force.
Long range force act without touching (e.g. gravity) while the contact forces act (obviously) when the system is in contact with some other object.
It should also be noted that a force (in Newtonian sense) involves a pair of bodies. As soon as you identify a force, you should immediately try to find the two bodies involved in the interaction.
