Follow me call custom prompts not found and then fails

Delighted to see follow me hunt groups in this version (6.1.1.10) but mine fails if I try and specify custom voice prompts. Having done so the script falls over and goes straight to a default mailbox prompt (as set I have to say) and delivers the caller into the voicemail box.

Having set the custom voice prompts I have to completely delete the script and create a new one with a different name before it will work again.

I get this in the logs –

[Jun 27 09:37:50] WARNING[6232]: file.c:665 ast_openstream_full: File ../ogm/gtf
ollownext does not exist in any format
[Jun 27 09:37:50] WARNING[6232]: file.c:995 ast_streamfile: Unable to open ../og
m/gtfollownext (format 0x4 (ulaw)): No such file or directory

Although the files in wav format are in /var/lib/asterisk/sounds/ogm:

Any ideas?

Kind regards,

Geoff.