It needs 2012+ to work, i think. And make sure that your map is built with stampertools. (pretty sure eczeds mappack or modpack has a stampertool map) Tried this on a project 7 client, somewhat works.
2012+? Where can I find a working 2012+ client? Also I wanted to play build to survive the zombies with the built in stamper tool but it wasnt working, do u think its because of the version or what?