Prerequisites
A failed check is useful evidence; capture its message and the smallest reproducible input.
Steps and expected result
For ValueError converting net_cents, inspect the exact offending value and source row. For KeyError, compare required header spelling and accidental spaces. For no rows, inspect filters and status case. Do not use a blanket try/except that turns every error into 0.
Verification
Check the input row count and case control totals before attempting a larger exercise. Record your operating system/tool version when asking for support. Never include passwords or private source records.
Independent check
Explain which output proves the setup works and which capabilities remain untested. Do not disable security settings to make an exercise run.
Try the activity before reading its reference. Keep your sources, commands and assumptions with your work. Companion activities are unsaved self-practice and do not award a certificate or change lesson progress.