I either used "fillet between two surfaces" and also "chordal fillet"; both have the same effect and fillet is done reversely with an edge ( along with two parallel patch). Of course after I deactivated trim 1 and 2. When the trims are active nothing happens except some error messages.
Can you make a section layed down on the edge you wanted to fillet? I think there are 2 surfaces actually folded close together. Or you can also save a stp or igs file here and let us check it. It should behave the same way on any PC.
I deleted the folded surfaces but the result was the same. After working a lot it made me tired because I think the shaping was wrong from its starting point with a series of unprincipled pieces. this caused that it turns into Frankenstein! As it made me confused like a complicated puzzle I had to delete it completely and started a new one carefully with regard to catia rules, though this one had a small failure as well ( width place of the front light and a wrinkled fillet near the place)
There are several solutions for your problem.
1 - Use "Shape Fillet" with G2 mode and click on trim button for both side. It will give you a nice and smooth fillet, but this feature can be tricky, it does not always work depending of your shape.
2 - Use parallel curve, split and blend. This method is a bit more manual and heavy to use, but it work most of the time.
3 - Same as 2- except that your sketch the curve and you project it on the surface. Takes even more time, but works.
Thank you PLM for your helpful advises. I deleted the shape inevitably but if I encounter the same problem next time, I will use your instruction certainly