pic-pgm2, pic18f4520 and picprog on linux question

I'm trying to program a pic18f4520 using a pic-pgm2 from olimex and 
picprog on linux.  I've set the device to be a pic18f452 for picprog, 
not sure if this will work. It starts to write and the LED on programmer 
comes on, but I get a verification error:

'0x000000: panel 0, block 0000, byte 0: verification failed read 
<value>, should be <other value>'

The value it reads is 0xdd .  Running the erase command seems to 
complete successfully and it seems to be able to read the device id from 
the chip as 0x1081.  If I try to read the chip picprog takes a long 
while and eventually returns what appears to be a hexdump.  Any 
pointers?  Will setting the device to be a pic18f452 work for a 
pic18f4520?  Any simple test other than writing that I should try?  Or 
should I look at another app?  Thanks.

-Ezra