Sambal Tumis Pahit

i was eating with my nenek when i wanted to try the sambal tumis. when i tasted it, i actually didn't wanna say that its not nice, but my nenek asked me is it not nice? too pahit? so i said yes lor. i told her i guess there's an ingredient that was too less. she did not agree.
she said that she herself do not know why its pahit. first she tried lessen the bawang putih, then she tried lessen the belacan, still taste very pahit. i suspect she forgot to add in the sugar.