Problem with .dct generation

[Grey]

Hi Group,
Excuse the lengthy post but I've been at this for days!!!
My mum has a One XL (32M RAM) which I bought her back in 2008 with Australia_7.20 (I think map). It has been going great but she decided it was time for a map update.
After a few "updates" using TomTom Home (it hadn't been connected to my computer for a while!!) I ended up with Navcore 8.010.
Whilst all that was going on, I found an Australian map (910.4895) along with the appropriate meta which according to the compatibility chart, could be used with 8.0.10 AND my PDA (running 7.45).
I generated a .dct file for my PDA using tt7_keygen.exe (it's old but still works for me) and that map was now useable on my PDA.
When it didn't work on the One XL, I found that I had to use a patched ttsystem file. When I couldn't find a patched system file, I then found some programs that did patching but didn't work on 8.010 and up. I tried a few different versions of Navcore 9 which didn't work until I came across a version specific for the 32M version of the XL (9.170). At least I could now use the thing with the old map now!!
After more poking around, I came across fastactivate. I can update the meta.txt file but when I try to patch the map, I get a .dct error and there is no .dct file generated. I've run fastactivate on my PC, from the root of the XL's SD card and from the directory on the SD card where the map is located.
If I try to patch the ttsystem file (Option 3), FA tells me it has been patched.
Not sure what to try next and was wondering if anyone else had any ideas.