reporting services - SSRS hide textbox based on number of rows in report -

i limiting report 10,000 rows in query (top 10000) because if don't specify parameters (default selected) takes forever run , honest isn't useful.

i created textbox in body of report @ bottom below tablix. report has no groupings or totals or anything. set hidden property "=iif(countrows("mainquery")>=1000,false,true)". text "more 9999 results returned. report truncated."

i out of scope error. when put countrows("mainquery") value of text box, give me value fine. why doesn't expression?

use count("mainquery") instead of countrows. countrows required refer current scope.

update: count work report single dataset. report multiple datasets have specify scope in expression, so:

=iif(count(fields!anyfield, "mainquery")>1000,true,false)