hi mohamed ,
as already specified in the thread ,http://scn.sap.com/thread/3286933 you can use the deprecated rfc , as even we were not able to solve that issue even though we deleted and reimported several times , you can use deprecated rfc . we tried changing the type of the attribute from xtring to other compatible types at abap side but it didnt work , so we used deprecated rfc.
Regards
Govardan