Visual Administrator Error: End of stream is reached

Dear SDNs,

When I startup the visual administrator via clicking "go.bat",the system raises a message in Dos "Variant Jave_home is not set".But the visual administrator still can be started up.

When I try to connect the default SAP J2ee engine with the correct account and password, the error "End of stream is reached..." is raised ,so I can't logon.

How could I correct it?

Any reply will be appreciated.

Thanks!!