i would get onto your vets and get some formula milk and try syringe feeding it to give it a start .sadly years ago i had this problem with a kitten she lived till she was 6 weeks but i still lost her the mother seemed to know there was somthing wrong with her and did not bother with her i hope you have better luck with yours
So far so good with the others, the mother has moved them all into my daughters bedroom draw, I think that perhaps its quieter there, do you think this is normal behaviour?