Before using for the first time, the acrylic markers must be activated as follows: First, shake the marker vigorously with the cap still on, then remove the cap. With the nib facing down, prime the pen on a piece of test paper, carefully pressing down on the paper a few times until ink fills the tip. The marker is now ready for use. 

Special note on the edding 5000 acrylic marker broad: Always pump along the entire length of the slanted chisel nib, not just on the point of the nib.