I've applied it on previous models when the curve was attached to a solid body, but I can't seem to apply it to a reference curve.The following looks tangential but its not mated, which is required to adjust the angle of the green component while maintaining the tangent connection. In another assembly the mate worked when applied to the edge of the green curve, but in this assembly the green part is tapered inward such that the curve changes in 3 dimensions. I added a reference curve (grey curve) that varies in only 2 dimensions, matching the curve of the surface, yet I can't apply a tangent relationship. Any guidance to get the grey block to mate tangentially with the green curved surface would be greatly appreciated.
EDIT: Sorry i didn't add the part files for the assembly, updated the zip file - if someone could give this a look and offer some advice, I'm sure a lot of you experienced modelers should know what to do. If it's not possible please say so..