KF Some kind of error i just can't get through.

Hello, i am having a problem with my RPG version (thanks for WPC for making the IDRPGMod btw.)

So i was compiling a version i downloaded of the internet but it gives an error ;

Error: ObjectProperty PissJaRPG.ID_GUI_Tab_BuyMenu.IDItemInfo: bad cast in 'ID_GUI_Panel_ItemInfo'PissJaRPG.ID_GUI_Tab_BuyMen u.IDItemInf''

Any help? i looked into it but i can't see the fault