I am trying to add some flat out sealant to my rear wheels

[racer86y]

It acts like there is a check valve behind schrader valve on rear wheel.I take a small screwdriver and it seams like it pops something open.But the minute i start squeezing bottle to put fluid in it closes again.Any ideas of what i can do to put sealant in?

 

[North Idaho Wolfman]

You need to pull the top off then add liquid to the stem.