Sharepoint 2007: list calculated column calculate days between 2 dates

For a Sharepoint 2007 list

I would like to have a calculated column that calculates the days between 2 dates.

Prerequisites:

• We have a Sharepoint 2007 list
• We have at least “design” level permission (Can create lists and document libraries and edit pages in the Web site)  to the site where the list is located
• we have 1 column called  [Scheduled GMT] (default Date and Time type)
• we have 1 column called [start_date] (default Date and Time type)

We now go to -> Settings ->  List Settings -> create column

1. give the column a name “ex: Days left”
2. The type of information in this column is: “Calculated (calculation based on other columns)”
3. in the Formula field insert:”=IF(ISERROR(DATEDIF([Scheduled GMT],[start_date],”d”)),DATEDIF([start_date],[Scheduled GMT],”d”),-DATEDIF([Scheduled GMT],[start_date],”d”))”Where [Scheduled GMT] is the column with the GMT Time and [start_date] is the column with a start date for the calculation.
4. Add the new column to your view of choice to see the automatically calculated days between the 2 dates.