QUESTION:  When I run some commands in InCAD, they tell me that they do not work. 

 Example:

Command: _cont_interval Unknown command "CONT_INTERVAL".  Press F1 for help.

or

Command: _CELEV Unknown command "CELEV".  Press F1 for help.

 What have I missed?  How do I fix this so they will work?

ANSWER:  When you first loaded and ran AutoCAD, you were probably presented with the following dialog box.

As you can see, it has 2 options for you to choose between.  If you pick the first one (which is the default) then the ACAD.LSP file is not loaded with every drawing you work in.  This means that any commands that are activated by the ACAD.LSP file, will not run.  This is what you are running into.

 We recommend that you pick on the second option so that the ACAD.LSP file is loaded with every drawing so the InCAD routines loaded with this file, are available to you all the time.

 There is also an option to turn this question off so you are not bothered by it all the time.  If you did turn this off then you will not be asked which option to use.  This means you can not choose the correct option now.

 "So how do I fix this?", I am sure you are asking. 

 There is another way to turn on the check mark to force AutoCAD to load the ACAD.LSP file with every drawing.  Go to the TOOLS menu -> OPTIONS and you will get the following dialog box on screen. (Or type the command, OPTIONS on the command line)

 Pick on the System tab at the top of the dialog.  Then (as shown above within the red oval), ensure that a check mark is placed on the option "Load acad.lsp with every drawing".  Then pick on APPLY at the bottom and OK to exit the dialog.

 Now all drawings opened in the future will automatically load the ACAD.LSP file so all the InCAD commands will be available and working.