You didn't mention which extender or which function. Can I assume you are using the Process Extender function tRemoteConn?
If so, when monitoring remote computers, note that the remote computer will only allow access to user accounts that have permission to access it. Error 235 indicates the function is unable to connect to the specified computer. This could be caused by the computer not being on, not supporting PDH, not being connected to the network, or having the permissions set on the registry that prevent remote connections or remote performance monitoring by the user.
Make sure the remote computer allows remote connections and remote performance monitoring.