Is It Normal To Have Bend In The Knee While On Fiberglass Cast?

Hi i've had a fibreglass cast on my leg for a week and a half now. When i last had it checked at the hospital they wanted me to start walking on it soon. I've tried doing so but i'm finding my foot is not at the right angle in the cast to walk in it. I'm either walking on my toes which i'm finding i can't put alot of weight on that way, or my knee is bent inwards not allowing me to walk forwards. Is this normal? Or should i b thinking about going back to the hospital to sort it out?