Fishing line diffuculties?

i just took off som old line an put on som new 1 myself. (25 lb test monofiliment) im preety sure i put it on correctly and its tight on the spool. this line is better than my old 1. its my first time puting line on. i casted it but it doesn go that far an makes a funny noise wen it goes out. it doesnt reel in that tightly and wen theres som dangling between the reel an first guide it gets tangled up all around the reel pretty easily. my real says its meant 4 20 lb test an under but a 5 lb test i think is not goin to make that much of a difference. anything i did rong? any advise please?