Wa'alaikumassalam sis! Alhamdulillah scan okaylah, tu yang penting, sometimes at 26 weeks the doppler memang tricky to find, especially if placenta position or baby's angle tak cooperate, so jangan worry sangat, it's very normal and doesn't mean anything is wrong. A lot of moms experience this because the doppler kena find the exact spot, especially kalau baby moving around or placenta depan. Kalau scan shows baby's heart is beating well dan baby active, tu dah bagus enough, though if you're feeling anxious about it, best ask your nurse or doctor to do a quick recheck next visit untuk peace of mind, okay?