Listing my car on a classified add

Question

i have completed all the fields and uploaded my pictures i have selected a classified add when i go to list the item to sell it appears in a red box at the top of the screen " YOU CANNOT SUBMIT YOUR LISTING DUE TO THE FOLLOWING PROBLEMS"
. AN ERROR HAS OCCURED
. PLEASE ENTER A VALID VALUE
this has never happened before i have cleared my cache and cookies but still i cant list my item