[syslog-ng] substr function issues

[westlake]

I'm stumped on a little problem with syslog-ng, basically what I'm 
trying to do is extract text from a string and place that into a new macro,
eg
-> set($(substr ${MSG} 7 12), value("${MACRO");

here the syntax checker stops short around the first dollar sign and i'm 
not sure how else I can apply this.

thanks