Have u placed any tiles? If so, how did u delete them? Because if it was by grabbing a blank tile from the sheet and covering them, then that didn't work correctly. This time, create a new scene (and delete the old one) and now try it. From now on, click the mouse selection tool on the left side and click on the tile u wanna delete, and then hit the delete button on ur keyboard (or backspace). Upload ur game as unfinished to the Stencyl Arcade and people can help u. Also just in case, i would like to see ur movement code.