12d Model

i am using autocad 2013 and 12 model 5M 10.0c1e (nt.x64) version. and when i tried to import strings from autocad to 12d through data input from file i/o menu, it says invalid file version.

Hi,
can anybody help me to create kerb return coz i m trying to provide property acccess to the main road....

Thanks in advance