Thickening errors on mesh file converted to surface

I am trying to create solids from scan data(stl or obj) in the typical fashion suggested by Solidworks. "Mesh wizard> Surface wizard > Knit all surfaces > Thicken" I am eliminating all the topographical errors and intersections with the wizards before I get to the thickening step. Although my surfaces do not contain errors I keep getting errors when using the thickening tool in the final step. "Failed to offset or face could not be deleted" is always the message. I am not sure if I need additional prepwork on the surface before doing any thickening. I have two sample files in which I have done this and have the same result no matter what.

Thanks,

Shawn

SolidworksSurfacing