I get right to the end of the installation and get this error:

[root@localhost Linux]# /sbin/modprobe truecrypt
FATAL: Error inserting truecrypt (/lib/modules/2.6.21-1.3228.fc7/extra/truecrypt.ko): Unknown symbol in module, or unknown parameter (see dmesg)

When I try to decrypt a TrueCrypt volume I get the following error:\

insmod: error inserting '/usr/share/truecrypt/kernel/truecrypt-2.6.21.ko': -1 Unknown symbol in module
FATAL: Error inserting truecrypt (/lib/modules/2.6.21-1.3228.fc7/extra/truecrypt.ko): Unknown symbol in module, or unknown parameter (see dmesg)
Failed to load TrueCrypt kernel module

I'm assuming that the second error is a result of the first. Any ideas how to fix this?