In the center of the Submission page, above the structure editor, the detailed status message (bold and red) about the submission is displayed (see figure 2).
Examples for detailed status messages:
UnBalancedCharge - The structure seems to have a charge balance problem
StructureCheckerError - Acylhalide_substructure_found: 1 substructure found
PositivelyChargedStructure - A positively charged structure was submitted, possible structure -> salt proton transfer to be checked by registrar