The correct spelling is agreeing.
The -ing form is waving.
You would spell value with -ing on the end as valuing.When you add -ing to a verb, and that verb has a silent E on the end, you get rid of the E.
riding
Typing
Tiering
Practicing
end ear ing
eye ehn gee
planning
centering
Picning
Chase+ing is spelled chasing. You drop the 'e' and add '-ing'. The cat was chasing his tail.