Help with DateDiff function

Is big but plese try to help me :

I have one database with this structure and one big

trouble:

Field Name - Data Type

Employee Code Text

Employee Name Text

Date Date/Time / Format : Short Time

In Date/Time / Format : Short Time

Lunch Out Date/Time / Format : Short Time

Lunch In Date/Time / Format : Short Time

Out Date/Time / Format : Short Time

Day Total Date/Time (Expr1: Sum([LunchOut]!

[Lunch Out]-[Check In]![In]+[Check Out]![Out]-[Lunch In]!

[Lunch In]) / Format : Short Time

REPLAY :

The problem is in how Access stores date/time values. A

Date/Time is really designed for *a point in time* - not a

duration. It's stored in the database as a Double Float

number, a count of days and fractions of a day since

midnight, December 30, 1899 - so if you subtract two

date/times you'll get days and fractions of a day; if you

add these up and the sum comes to over 24 hours, it'll be

a time of day on *December 31, 1899* - as you can see if

you format the sum to Long Date! Instead, I'd suggest

using the DateDiff() function to calculate an integer

number of *minutes* - signified by n for miNutes, since m

means Months - worked. Your Day Total expression could be

DateDiff("n", [In], [Out]) - DateDiff("n", [Lunch out],

[Lunch In]) You can then sum this across records using a

totals query. To display the result as hours:minutes, you

can use an expression like ShowTotal: SumOfTime \ 60 &

Format(SumOfTime MOD 60, ":00") where SumOfTime is the

total from your query.

I did this suggestion and my Day Total change to :

Expr1: DateDiff("n",[in],[out])-DateDiff("n",[lunch out],

[lunch in])

Work but in one sum like that :

In : 9:20

Lunch Out : 12:30

Lunch In : 13:05

Out : 18:00

The real total is 483 but this Express give one total 485,

another sample

In : 9:25

Lunch Out : 12:36

Lunch In : 12:50

Out : 17:59

The real total is 492 but this Express give one total 500.

PLEASE ANY HELP

Fernando Salgueiro