Script Batch plot Problem

I use a scripting program for batch plotting.
The problem I'm having is when running the script it
comes across an open drawing in the batch; the script
doesn't know how to deal with this. The question WOULD YOU
LIKE TO OPEN THE FILE READ-ONLY could be answered YES with
the first line in the script and it would solve it but when
it gets to an unopened drawing having YES as the first
command stops it in its tracks.
Here's the script file I'm using
TileMode
0
-PLOT
y
Oce TDS400 Roll 1.pc3
ISO A1 (841.00 x 594.00 MM)
millimeters
Landscape
NO
Extents
FIT
Center
Yes
A1.ctb
Yes
No
No
No
No
No
Yes
I don't know much about LISP but maybe a bit of code at
the start could solve it.
Thanks
Mik