00 using mityvac on brakes having issues

[comet240]

hi I just bought yesterday the mityvac one person bleeder so I jacked up the truck and did the rear ends I did about 2 1/2 bottles for each side as I wanna suck them through thourghly but it seems to stop sucking more fluid and when I poor back into the resvoiour I have more then I put in... so what am I doing wrong

and how come there is little pieces of crud in the resivour I l sucked out best I could do too

but why isn't it sucking right through