Our guess? You're using the wrong cutting surface.
You should never cut on hard surfaces like glass, ceramic tile, ceramic plates, marble, granite, or acrylic -- all of those will dull (or even chip) your blade very quickly.
Always cut on a surface that can "give" under your blade. (If the edge of your knife can leave a cut line in the material, you've found the right surface.) We use cutting boards of wood or polypropylene.