HELP!! fixing lumen prints

Hello! Can anyone tell me please how can i fix lumen prints without loosing those beautiful colors?
First time I've tried to fix with Tetenal Super fixer (which is the fixer i use for film and it works really good) it bleached a bit the image and lost color turning ligt brownish, then i tried to fix with sodium thiosulfate (about 100g/1Liter) but it affects the same way the image as tetenal... so, these are my questions:
-am I doing someting wrong?
-how many time do i need to get the image correctly fixed with sodium thiosulfate and wich is the correct proportion to mix?
-Is outhere any better fixeri can use for it?
-what about toning the image? before or after fixing?

I´ll appreciate all your help. thanks.

Hello irakononenko!
I have the same problem. I found no other solution than scanning my lumen pre-fixing (it doesn't affect the lumen at all). Then I fix & rescan, so I have two lumens! (mostly I don't rescan after fixing though as I find the lumen not as beautiful.) The only way I know to keep my lumen "original" is to scan them before I fix them & then make a jet ink print.
Hope that helps a bit, if you hear of a method tp fix it without changing the color, please let me know.
Eleni