FOSS gamedev and creative worlds

trying to use the function minetest.env.punch_node i do always get this error
bad argument #1 to 'punch_node' (userdata expected, got table)

using the same variable in for example minetest.node_punch doesn't create problems i fail to understand my mistake :P

It is minetest.env:punch_node (with :, not a .) I think.
I had the same error :D

thanks