I need some help figuring this out...sm - Wondering

I posted a week or so ago about a job offer working for a court reporting agency.  It is transcription that pays 5 cpl on a gross line.  The work is actually doing claims for insurance companies.   She wanted me to come a week ago before I started just to see how fast and well I could transcribe. I typed 7 pages in 20 minutes, which equaled about 127 lines.  So I figured, wow 127 lines in 20 minutes, that's great.  I'll do just fine at this job.  Well, fast forward to this past Monday when I started my first day.  I consider myself to be a very fast transcriptionist.  I work at a local hospital doing radiology at night.  I can transcribe anywhere from 250-300 lines an hour and just the other day I transcribed 350 lines an hour at .15 cpl.  This is on a 65-character line too.  At this job at the court reporting agency, it's all I can do to get to 250 lines an hour.  I am struggling to get even that.  Today I worked for 7 hours, took 1/2 for lunch, and typed a total of 1,361 or somewhere around that.  When you do the math, it sure isn't a whole lot of money, somewhere around $68 for 7 hours.  This job pays on a gross line.  Can someone tell me why the heck my line count would be so low even being paid on a gross line?  I was under the impression that being paid gross line versus 65-character is so much better.  You get paid for even one word on a line so wouldn't the lines rack up fast?  If I can do 250-300 hour on a 65-character line then why wouldn't it jump to 400-500 lines an hour on a gross line?  I haven't made under $15 an hour in almost 20 years.  At 47 years old, I can't see myself transcribing to the point that my wrists are cramping and aching (which they never, ever do at my other job) for$12 or $13 an hour.  That is just crazy.  I made that almost 18 years ago.  Does anyone know how to figure this out.  I am racking my brain as to why I can't get the line count that I think I should be getting.