RegisterStartupScript on ascx

[rom]

my main aspx page has 3 user controls. they are all
located in the same place of the page and each time i set
the visibility of 2 of them to false and 1 to true. now, i
want to use the RegisterStartupScript on one of these
controls but then i write page.RegisterStartupScript i
registers it on the aspx page and i get js errors on the
other controls. when i try me.RegisterStartupScript (on
the ascx) i get "RegisterStartupScript is not e member
of....."

help...