When I try to block I get Invalid ID

[sandsofife]

I have had trouble  with a buyer he bough but didn't pay and now he has bid on another item  so when I try to block him I get an Invalid ID

[peridot55555]

Have U put in a space before or after the ID?  

Have U put CAPS or vica versa, or is there a capital in the ID that U have not put in?

Someone more experienced might know if U have to cancel the buyers bid first.