why wont my variable increase?

hi I have the following script which needs to increase the nextpage variable from 2 to 10. However the script never seems to increase and the scrape session runs continously.

//Create the loop to go from 2 to 10.
NEXTPAGE.clear();
for (int i=2; i<=10; i++)
{
// Make the current number available to the session.
session.setVariable("NEXTPAGE", String.valueOf(i));

// This line will just write an output to the log, but is otherwise unneeded.
session.log(" ***Starting PAGE COUNT " + session.getVariable("NEXTPAGE");

// Finally scrape the file for this CATID.
session.scrapeFile("collect video");
}

it may be that I set the nextpage variable on initially running the scrape to 0 and it appears that I cant reset this?

Or is it that because the script calls a scrapable file that call another scrapeable file before going back to the script?

Please Help!

thanks