#Ref error cant work out the reason

Hi I created an index lookup table and for some reason one range returns an error when it is over 799 for the width range it returns the #ref error and I cannot for the life of me figure it out. Can someone please advise of what I have done wrong I am not the best at excel and this is extremely frustrating. Any help will be greatly appreciated thank you TEST V WRAP.xlsx

Thank you for the quick response. They all work well I still have no idea why it didnt work in mine but it is sorted now.