Quote Originally Posted by George1992 View Post
Thank you!

As for the довольный, why is it incorrect in the sentence?
Difference between full and short versions of adjectives can vary and be frustrating. Probably it is subject to remember.
In this case it can be thought that "довольный" is indefinite form. For example "Toy has label 'довольный слон'". We don't know why. It is just state.
"Доволен" is more definite and often is used in joint with answer/reason "why does he is satisfied?". Even if this reason in sentence is omitted, but it is clear from context. For example:
Кот попил молока и (поэтому) он доволен. ("доволен" is preferrable)
Кот попил молока и сидит довольный. ("довольный" is preferrable because we shift attention from state "доволен" to action "сидит")
-Он видел предложение? -Да. Он доволен (предложением). (because of context "доволен" is preferrable)
In you case first form of sentence is ill-formed for native-speaker. There is strong "why?" joint here. However in many cases (like above) interchangeability is possible.