The crosstab is just going to give you those values found in the intersection of the row and the column. What is your one group? If the group is based on location or sequence, make sure you have created this as a group within the crosstab. After adding it as the row or column field, click on it, and choose group options and recreate your group there.
If you have the crosstab in the report footer, it will use the values from the entire report, so if the location is represented in multiple row groups (this assumes your group is not on location), e.g., the maximum function will pick up the maximum across groups as long as it meets the location and sequence criteria.
Similarly, if values for sequence are repeated per location because of your grouping, the crosstab will pick up the maximum for that sequence at that location. So it would also be helpful to know what "sequence" is--a table field? A formula? Is it a datetime or a number field representing order?
If you place the crosstab within the group footer, it will limit the values to the specific group, but then you will have a crosstab repeating on change of group.
-LB