I got just the answer I have the same problem but u don't have to yell just think it! Think as if u were yelling and how it would sound it work the same in a dream!!! I was wondering if anyone had this problem! Also I couldn't lift some stuff in my lucid with my arms as if I were so tierd I just couldn't so instead I just said I don't have to lift anything with my mussels an then I just thought about it lifting an it worked. Let me know if that's any help buddy