Why doesn't this macro work every time?

Ok all you clever people.  This one has got me stumped.  I hope I am posting this in the correct place;

I'm trying to write a macro that draws a closed polyline on a layer named "capping".  This will then be used as the profile for the sweep command.  Here is the macro;

^C^C_-layer;s;capping;;pline;-12.5,0;-12.5,40;7.5,50;67.5,50;87.5,40;87.5,0;c;   (the 'capping' layer will always exist in the drawing template)

It works great 80% of the time but every so often the macro will miss a point, sometime two, and the polyline will end up the wrong shape.  I've tested this with a couple of users on different workstations.

Any ideas?