Setting LineWidth when exporting a figure using 'print'

I am trying to export a figure using the print command. The figure has several line plots on it. I have set the LineWidth property of each line to be 2.5. When I export the figure, the LineWidth becomes significantly smaller. In fact, it doesn't matter how I set LineWidth before exporting, I always end up with the same skinny lines. Please help! Here's a portion of my code.

    lines=get(gca,'Children');
    set(lines,'LineWidth',2.5)
    print(f2, '-r1200', '-dtiff', [PathName FileName])

I am running version R2012a (7.14.0.739) on a 2012 Macbook Pro.