Cause
You created specific project structure and defined identification blocks to which you assigned structure identifiers. Now there are conflicting structure identifiers for the placed part and for the corresponding mounting panel, in one of the identification blocks.
Solution
Enter the same structure identifiers in the identification blocks for the placed part and the corresponding mounting panel (in the Properties<...> dialog under Displayed DT) (e.g. for "Higher-level function" and / or "Mounting location").
Start a new check run.