Thank you for your reply, but that didn't solve my problem. It is true that ASEL command is not enough. I already had used Asel and following that nsla,s and esln,s to make sure only nodes and elements attached to an area are selected.
If I select the nodes at the bottom of the model where I have fixed support, whether I select the nodes at the bottom or just the elements at the bottom, the FSUM command gives me 30 N force. But It doesn't happen if I select the elements on the soft material, plus the nodes on the interface surface which is the housing. That is the region where the bonded contact is happening and I thick the reaction force between the soft material and the housing surface must be equal to the applied load on the rollers. But it give me zero force again. How is possible that loads are applied to the rollers and the reaction force in the contact region is zero by FSUM command? I also selected the contact elements at this region to see if the contact pressure is as I expect. It looks logical that pressure is higher at rollers positions. So how it is possible my forces are zero at the interface region or on the soft material? Any help is greatly appreciated.