InfoServ - error 404

I am having issues flashing my Dm800hd sim201, I have been having problems with flash memory space for some time now, so I decided to flash with a old image to see if that would help. The box is working fine with this image installed sim201e-76-gp5.00-OE1.6-dm800-20100429, and I can communicate with the box, but it will not go into flash mode now. I am currently trying to flash with optiflasher, and I have tried a few images but keep getting the same error message,OptiFlasher Error: HTTP/1.0 404 Not Found. Can you point me in the right direction to reflash successfully. I haven't tried dreamup yet, mabe that is the only way.

many thanks for any advice....sergio.

Just a update, I managed to get the box back up and running, but I had to use dreamup and a lot of patients.
Optiflasher would not go past phase1.

But thanks for your support Yassinov, I think optiflasher is a very good tool.

cheers......harryg