[senco-forum] can't name colours despite lots of support

Have a 5 year old boy in my class who has been struggling to name colours all year. He can sort into different colours and can consistently name black and white but no others. We have tried using his love of Chelsea to get him to recog blue, but he just calls the shirt colour 'Chelsea'. I have tried PORIC (e.g  a week identifying red/not red). We are delighted because he then finds all the red objects in school. Then we moved onto green and now everything is 'green'.
Have not had a child unable to name colours this late in year. He has no trouble naming other categories e.g. animals, food
Any ideas as to why he has this particular difficulty and how I can help are welcome (still a week to go!).

Kitty