Hi, which version of LDT are you using? This lisp was last updated for use with LDT2008.
And I'm not sure how, after 8 years this has been posted, no one has caught this ommission until now. If you add the following bit of code to the very top, or very bottom (before or after any of the existing parenthesis) it should load and run on versions up through Ldt2008.
Sorry about that. I have a number of helper routines that I load in acaddoc.lsp. Normally when I post these routines I make sure to include those that are needed, obviously I missed a few on this one.
Attached is a revised version with the get_space function included. In order to save time, feel frr to email me direct if you still have problems (I no longer have LDT installed to test this with, so I'm counting on you to tell me what it still needs.....I hope you are OK with that.)