Hi Anil,
LU1834 means "The HTTP transfer failed because the requested file did not exist on the server."
- What version of SEP are you running on the SEPM?
- Also: what exact file is resullting in that 1834 error?
Most likely, the SEPM is looking for (for example) SEP 12.1 content and the LUA is configured to download and distribute SEP 11 contents.
Another possibility is that the LUA server is downloading the materials but no distribution job is scheduled to put the in the place where the SEPM picks them up from.
Like Pete wrote, the log.liveupdate will tell more.