I keep getting warnings everytime I try to use FloXpress in my model. It's a showerhead, and basically I keep getting messages like "The geometry is not ready for the flow analysis." and "The model openings must be closed with lids." How do I find the cavities I need to cover? Also, how do fit the lids to some of the cavities? Some of the visible holes have a unique shape, so I covered them with rectangles, but the FloXpress is not working. I'm very sorry if this is a no-brainer, this is my third day of using Solidworks, so I'm not very sure how to use this feature and how to deal with these messages. Thank you!