Yes, in Batak you must follow the suit that was led if you hold a card of that suit. The first card played to a trick sets the suit, and every other player has to play the same suit when able. Only if you are completely void in the led suit may you play something else, such as a trump or a discard. Following suit is a strict rule, and it is what makes card counting and planning matter, because you can track which suits opponents have run out of. Playing a trump or an off-suit card while you still hold the led suit is not allowed.