And I hit a mental block...well not so much block...I know the theory...but.....it's not working....so I changed a million settings and moved the flash and moved me and changed some more settings.....
and on it went...
Well I have had to stop because my batteries went flat...So I will ask you Ladies and Gents....Please help...ALL OF YOU....


So here goes please be patient.

Part1 by SUNR15E, on Flickr
I'm pushed for space so 10ft is all I have...But I know that is not the problem...
Looking at the above setup...I get a great silhouette of the subject in the center of the room with little to no bleed of light breaking the silhouette....this is great....the backdrop is almost perfectly white (I will work on those settings I know I can fix that).
BUT

Part2 by SUNR15E, on Flickr
Can you tell me what SHOULD happen when the flash on the camera fires. I have read loads and I think I have the idea set up correctly in my own head....BUT...in practice something is not right...
The camera is set up to allow the flash behind the subject to overexpose the backdrop.
I will add more about what I think should happen and also what is happening Once I have a few theories and answers here first if you don't mind.
So in summary.
In the above setup
What should happen?
What should the final picture look like if the camera flash fires?
Many thanks for your input...And yes I will be adding pics to show my fails....!!
SUNR15E