I have my System encrypted according to this guide

Now I have switched to GRUB2 and tried to adapt the code to chainload the TrueCrypt bootloader

Code:
menuentry "Windows Vista" {
       insmod chain
    set root=(hd0,1)
    chainloader (hd0,2)/truecrypt.mbr
}
When I choose the Windows Vista entry it loads the TrueCrypt bootloader, but says it is damaged. Could that really be the case or is that because my code is flawed?