A cumulative figure beside the first record of a new group can accidentally include the previous group's values. Check the report control's reset scope before changing the query that supplies the individual records.

Use a copied desktop Access report with one grouping level, GroupCode, and a declared detail order. In the practice data, group A contains Units 2 and 3 in that order; group B contains Units 4. Keep the ordinary Units field visible so each accumulated value has an inspectable contribution.

Configure the report control

In report Design View, add a Text Box in Detail. Select it, press F4 and use the Data tab. Set Control Source to Units. Running Sum set to Over Group resets at the next higher grouping level; Over All accumulates through the report. Choose a meaningful control name and label so this value is not confused with the ordinary Units field.

For the one-level grouped example, Over Group should display 2, then 5, then 4. The first B record is the decisive witness: its value starts from B's contribution rather than carrying A's five units forward.

In a separate comparison control, Over All should display 2, then 5, then 9. Label the two controls Group cumulative units and Report cumulative units. They agree through group A, so inspecting only the first page or first group could miss the wrong setting.

Inspect the boundary used by this layout

The next-higher grouping level depends on where the control sits in the report structure. Do not move a Detail control into a group section and assume the same reset boundary still answers the same question. Microsoft's example uses a field at detail level and an aggregate expression when accumulating group-level values.

For a report with nested groups, write the intended reset boundary in plain language and inspect a transition at each level. Retain the report's actual group and sort definitions with the acceptance example; a visually adjacent label alone does not establish a grouping level.

Finally, check the complete preview and its ordinary values against the source records. A correctly reset cumulative control cannot compensate for a record omitted before the report runs. Accept the layout when the first record after each intended boundary begins the right cumulative sequence and the report-wide result remains separately understandable.

Sources: Microsoft: report running sums.