According to the screencap, those 'jeans' are part of a material collection you must apply to 'Jeans for L'Homme'.  If you own the jeans, you must load those first before attempting to apply a material shader.  In this case, you are trying to apply the material collection to the L'Homme figure that does not have the matching material zones to accept the shaders.

Check the 'Dreamy Denim for L'Homme' webpage and look at the required products.  

BTW, under what category does those 'jeans' appear in your Library?