Can't Get Mirror to Work

I'm having difficulty with trying to mirror some lines and arcs with a VLISP program. See the attached jpeg for information.

The green lines are the items I want to mirror. Points pt12 and pt14 I have located in order to select these green items. Points pt15 and pt16 are co-linear and locate the mirror line I want to use. When I run the code it does not perform the mirror.

(command "._MIRROR" pt12 pt14 "" pt15 pt16 "N")

However, once the program stops I can manually enter these commands at the command prompt and it works just fine:

Command: mirror

Select objects: !pt12

Select objects: !pt14

Select objects:

Specify first point of mirror line: !pt15

Specify second point of mirror line: !pt16

Erase source objects? [Yes/No] :

Is there something I'm missing between the Command line and my LISP code?

OSMODE = 0 and PICKBOX = 0 when I am attempting this. The dashed yellow rectangle is just to show the area bounded by pt12 + pt14.

Use ssget to collect a Window or Crossing Selection Set, then pass this Selection Set to the Mirror Command.

Lee,

Thanks again sir. I'm researching the ssget command now to be sure these is not something I'm missing with using it in this process. Will report back.

BINGO --- I got it....

(command "._MIRROR" (ssget "W" pt12 pt14) "" pt15 pt16 "N")

Shesa workin' now! Thanks again.