Lower Trapezius Activation

hey, so ive finally managed to strengthen my serratus anterior and can do like3 scapular push ups now but i make sure i reach 30 in sets of 3 if i have to, but now im doing face pulls with thera band aswell as this and when i pull on face pulls i feel tension only in my bicep and not in my lower traps, is this normal or do i have weak external rotation?