You might have it set to multiple edge loops (5), try going to the tool settings and select relative distance from edge or equal distance from edge.
EDIT: Go into vert mode.. you might have deleted edges by just pressing delete instead of using the DELETE EDGE/VERTEX tool. This will be apparent if there's vertices and no edges where you're trying to use the tool. To solve this simply select the vertices you don't want and use the Delete Edge/Vertex tool (Polygons > Edit Mesh > Delete Edge/Vertex)