Hello. I am having difficulty creating a specific part. The part is supposed to resemble the attached image. Originally, I tried to make this part by sweeping the rectangular base along the curved path (which was successful). I assumed the top part would be made by sweeping the rectangular column along the same path.  However, the column failed to sweep. I later created the top part by extruding the column fully and using the extrude cut to make the path resemble that of the base. 

Is there an alternative way to make this part, or does anyone know how I can get around the issue of the column failing to sweep?