reporting services - SSRS - Show field in header but only when displaying first page of records for a group -

i have ssrs report have row group , groups details.

the row group grouped on customer number. group details contain order details

my report has 10 unique customer numbers. customers have multiple pages of orders, have 1 page of orders in ssrs report.

i need customer number show in header if report on first page (or first record) of orders particular customer number.

in other words, need show field in header when displaying first page of records group.

so if customer has 10 pages of orders in ssrs report, want customer number show in header on page 1 of orders, other 9 pages should not show customer number.

we not see customer number on ssrs report until next (different) customer number record appears again visible on first page of it's orders , on...

how can achieve this? possible?

update:

i going try achieve need using rownumber function. if it's on row number 1 show customer number, if not on row number 1 don't show in tablix. i'll make textbox hidden i'll call header textbox.

i need rownumber reset 1 everytime switches new customer...

i'll try out , post if works...

i found quick fix need find better more stable solution.

i put below expression in textbox , got me wanted.

=iif(rownumber("customernumber") < 34, "text want display goes here", "") 

i saw max number of lines per page report 33 "customernumber" row group. expressions checks if row count < 34 still on first page go ahead , show customer number or whatever text decide...

this break if layout of report modified more 34 lines can fit on page example why see temporary solution (just report out).