Dear Neeraj,
ok then there is other way around
create a user defined feild text type (page break)
then select this in the columns of the actvities table.
then put the values in the coulmn
like if you want the 1st WBS in the first page then say it as 1 then fill down all the activities which are to be in this group
then for the second WBS type 2 and then fill down
repeat the same for all the WBS like 3,4,5,
then after that go to group and sort select this user defined field (page break) in the top before the WBS .
then go to the font and color make the font size small and color as WHITE by this way you will not see this in the layout.
THEN PRINT set up options----page break settings -----click it
you will get the result...