Trying to sweep an extrusion with such a 'height' and profile difference in that small a gap will be a nightmare. You can make guide curves to for the sweep to better control this and maybe come up with a result that doesn't error out or create broken geometry, but it's going to look very odd.
What do you need to create this for? Are you making renders of this item with the weld blends? In other words....do you really need to create a crazy sweep protrusion in a tiny area to simulate something that might just be for a note on a process sheet?
Design Manager Streetscape Limited
Solid Edge ST10 [MP0] Classic [x2 seats]