jQuery Grid Plugin - jqGrid

Good! I pass a problem I have with a grid jqgrid.
I have two grids, a master / detail, such as master: student group
and detail: students

Students on the grid I have enabled the option to multiselect.

** When I run the action to delete by selecting multiple
record is sent by GET method ids separated students
coma example 22,33,55,122 etc thus eliminating me
selected.

** But when I release just sent me the first ids
Selection example: 22 This I need for example to change all
students selected a particular group!

Someone knows why this might happen, how I can solve?

Greetings
Ramiro