When a modal verb (see Modal Verbs if you need a refresher on those kinds of verbs) is put into the present perfect or past perfect tense ad there is a second verb following it, both verbs stay in the infinitive:
- Ik heb het gezien. = I saw it.
- Ik heb haar zien spelen. = I saw her playing.
This does not apply to "te+infinitive" verbs like proberen.
Duolingo Lesson: www.duolingo.com/skill/dn/Modal-Perfect