AVR-Chat

I struggling to program an AVR644 (40DIP) with AVR Studio 4.12 SP2, 
and an RS232 JTAG ICE programmer/debugger.  

Problem - AVR644 is not listed as a supported device for the JTAG ICE. 
Even though it apparently reads all the fuse and lock bits OK, 
programming ends in an error (FLASH Byte address is 0x00 should be 
0x0C).

I thought the AVR microcontrollers were quite intercompatible.  Do I 
have to buy a new programmer just for the AVR644, or am I doing 
something wrong?   I really hope I can program this with the regular 
JTAG ICE!

Many thanks for your help in advance,

Andrew