Graph's date

[an]

Situation:
A F_Form is based on T_Table.
T_Table has a Date field, formated with Medium Date.
The F_Form has a graph with the Date field, formated in
the graph with Medeium Date too.

Question:
When Load the F_Form with graph, the Date appears us:
Ex:
01-Aug-04 and 01-Sep-04 where the dates are 07-Aug-04 and
08-Sep-04.

Experiences with anothers Date they had resulted always
with the first day on the month.

Any idea will be appreciated.
Thanks in advance.
an