WebMethods Developer creating a flow service

Can anybody guide me in this problem:
WebMethods Developer Could not create “Simple:HelloWorld” com.wm.app.b2b.server.ServiceException:
[B2BSERV.0026.9103] unable to write to flow.xml

What OS?
What IS version?
Can you create any other service with Developer (Flow or Java)?
What account are you loggin in with?

Does the account that is running IS have OS privs to write to the directories under the package you are creating the service in? For instance the directory: /packages/MyPackage/ns/Simple/HelloWorld.