Have a look at the EpoApSvr.log file for errors when you are trying to do a pull.
What does it say?
Please...Help me. :-(
The above link details how to rebuild the entire repository. It's a bit extreme but might help fix your problem.
I'm sure in the past i've tried a much simpiler solution where you just delete a single file and run a replication and it dowloads the files without having to check all the packages back in again but i can't find the KB entry just right now.
Do you have any agent handlers in your environment?
Yes, I have one Agent Handler, but is Disable.
On 4000 workstations, just 500 have 6120 dat file, because to do update by browser and not by Repository. All other workstations has 6115 dat file version.
Also, in Agent Log, appear the message that "Unable to find a valid repository".
What's happen with all this things?????
I believe you have the issue described in KB 68414 .
The issue is fixed in Patch 4, which is due later this year - in the meantime you can open a case with support and get the POC mentioned in the article, or, if you're not using the agent handler at all, you could try removing it (i.e. uninstall the AH via add/remove programs and delete it in the ePO interface) - that might resolve it.