Couldn't get "Box in" or "Chip in" skills for Horward

wuyili

I am a new player and I chose "Horward", the center, as my initial playing character. However, I couldn't purchase "box in" and "chip in" skills for him. That is not a good news since the skills are kinda essential skillset for the center. Meanwhile, I could get them for the small forward, Erik.
Is it common? If not, what could I do?
Thanks,
wuyili

wuyili

Finally, got one from the random reward, however, couldn't get one from the shop still.