Making a commitment involves dedicating a resource to project resource plan.
Whether you are looking at the Resource Analyzer or Resource Planner, there is a slightly different definition of what will show as "committed work."
The Resource Planner shows Available, Committed, and Remaining hours in the lower grid.
When you select Committed in the Show Me drop down (in the Resource Planner lower grid), you see all the committed (public & approved) hours from all other projects' resource plans, plus (+) the newly entered hours on the current project's Resource Plan, plus any Personal time off hours. Personal Time off is considered (part of) the Committed Hours in the Resource Planner.
When you select Committed Work in the Resource Analyzer, it counts only hours (public & approved) from resource plans. Neither Pending hours (if using negotiations) nor Time Off hours count as committed hours, as there are separate buttons to select to show those hours.