From XL Help!!
DSUM(database,field,criteria)
Database is the range of cells that makes up the list or database. A
database is a list of related data in which rows of related information are
records, and columns of data are fields. The first row of the list contains
labels for each column.
Field indicates which column is used in the function. Field can be given
as text with the column label enclosed between double quotation marks, such
as "Age" or "Yield," or as a number that represents the position of the
column within the list: 1 for the first column, 2 for the second column, and
so on.
Criteria is the range of cells that contains the conditions you specify.
You can use any range for the criteria argument, as long as it includes at
least one column label and at least one cell below the column label for
specifying a condition for the column