It is an Obligation upon the One Who prays behind the Imam to follow Him
Question :
Is it permissible for a person to perform Sajdatut- Tilawah behind the Imam, if the Imam recites a Verse in which there is Sajdatut-Tilawah, if the Imam does not prostrate, and what should he do if he prostrates, bearing in mind that he is contradicting his Imam?
Answer:
It is an obligation on the one who is led in prayer to follow the Imam in all of his actions, so if the Imam prostrates, he should do likewise, and if the Imam does not prostrate, then neither should he.
It is not permissible for him to prostrate alone while the Imam is continuing his recitation; this is in the audible prayers, but as for the silent prayers, such as Zuhr and 'Asr, it is disliked for the Imam or the one led in prayer to recite a Verse in which there is a prostration, but if he recites it, neither the Imam nor those behind him should prostrate, because this is in contradiction (to the Sunnah) and it causes confusion. After he has performed the Taslim, he may prostrate.
If the Imam recites a Verse of prostration in the audible prayers, and he (the worshipper behind him) does not prostrate while the Imam prostrates, if it is due to ignorance, then it is pardoned, but if it was done with the knowledge that he should not do this, then his prayer is invalid and he must repeat that prayer. And Allah knows best.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 2 Pages 232-233