Problems with strumming

by Jo
(USA)

I have recently started learning acoustic guitar (an Ibanez acoustic) and I'm having trouble strumming the strings. Whenever I strum-more so a downward strum-I can blatantly hear my pick slide across the strings and it ruins whatever song I am attempting to play. I have tried using different weights, as low as .33 mm and as high as 1.14 mm (Dunlops)but have not heard any difference. I am holding the pick properly and making sure the pick is at an angle--as I know it can cause problems if that is not done--but still I can so easily hear the sound. I also have tried different speeds but it is still there and I don't know how to stop it.