XSD to class with svcutil ?

Hi, i built an application (contract first) and i want to extend it with
WCF-Service Support. I have a datacontract.xsd and a messagecontract.xsd and
i want to generate a class of it (like i did with xsd.exe for my asmx-web
service).
I tried to run the "svcutil -dconly" at command prompt, but i get only
errors (one of my complex types can`t get imported, etc.).
I don`t know, how i can declare the needed "[Data Members]" in my xml-file.??

Anyone an idea????
M.