A UCM based project is created and configured to poll for changes on the LATEST version of a stream.
The stream really exists and is tied to a branch whose type also really exists within the pVOB.
So, there is neither job's misconfiguration nor problem with the ClearCase environment.
Nevertheless, the build fails due to lshistory with the following message :

cleartool: Error: Branch type not found:<branch type>

The problem is that the branch has not been instantiated within component VOBs, just because there had been no changes.
It seems that this situation is clearly not taken into account by the ClearCase plugin.

A possible way to fix that can be one of the following solution:
1. Before the cleartool lshistory command, run the following command :
ct desc -l brtype:<branch type>@<pvob>
If the command returns no line with an "GlobalDefinition" hyperlink, it means that the branch type has not been instantiated. Then no change occurred on the stream
2. Run a cleartool find :
ct find <path name> -all -version 'brtype(<branch type>) ' -print
If the command returns no line, the branch type has not been instantiated.
<path name> should be those given in the load rules field

When the branch type is not instantiated, the lshistory command must not be run. And so, there's no need to run a build.
But it should not be shown as an error.