This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
As you've discovered, you can't nest tags like that--that's simply not valid JSP. You'd need to set the value to a variable and use either JSP 2+ EL, or the Struts EL tags if you're not running in a JSP 2+ container.