Good evening. I tried to upload the *.dae file that I exported from Google Sketchup Pro 6, and whatever I try; I get this message every time: "There was an issue with uploading your model to Shapeways. Your model has inverted normals in it. Normals tell us what the inside and outside of your model are(a good thing when we want to be able to 3D print your model). All the normals in your model have to be pointing in the right way. Inverted normals are also known as mixed normals or invalid normals. The fix for this depends on what kind of software you are using. With almost all packages you can easily visualize the normals so you can see whats wrong. Some packages have an automatic filter that can "flip", "invert" or "recalculate outside" and help correct this problem for you in a flash." I tried lots of things, but nothing really works. Can anyone tell me what to do?