Best way to repair a missing fillet in an imported part

Hi to all!

This is my first post, and i'd like to excuse if my English is not perfect!

I searched the forum, the training manual, all the documents i have, but i didn't find a good solution for my problem, and i'd like to know your suggestions...

I received a part where the fillet is missing, and i'm trying to find a solution of how to repair it. I thought to extend the surfaces, recreating the original shape, trimming away the portions exceeding the intersectiin and recreating the fillet ( I know the radius), but I go on in receiving an error..

So i want to ask you.. how do you usually repair a missing fillet??

Thanks in advance,

Cristina

SolidworksSurfacing