"No matching items found in your workspace" error in the TFS build

After creating MS Build Definition for a new branch I've got an error
"No matching items found in $/MyBranch/subDir  in your workspace, or you do not have permission to access them".
I was trying to find any permission issue for a build user, but  http://stackoverflow.com/questions/9210485/how-do-i-setup-tfs-build-definition-when-my-localpc-source-build-agent-and-de pointed me, that the error was caused by missing mapping.
To fix it it's required in Build Definition Edit open Workspace TAB and add folder mapping for a new branch in the table like the following
Source Control Folder | Build Agent Folder 
$/foo/bar | $(SourceDir)\somewhere 
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