[Exim] Exim 4.24 + quotas not working...

Please could someone advise me as to what would cause the following ?

I upgraded from 4.14 where my quotas where working fine.
The i discovered that the mail was bouncing because the quotas seemed to
be to low , after fruther investigation i found that the vaules i had set
previously where fine , when compared to those on the file system.

local_delivery:
driver = appendfile
maildir_format
directory = /home/mail/store/$domain/$local_part
create_directory
delivery_date_add
envelope_to_add
return_path_add
user = exim
group = mail
mode = 0660
directory_mode = 0770
quota = ${lookup mysql{SELECT quota FROM users WHERE
username='$local_part' AND domainname='$domain'}{$value}{10M}}
quota_warn_threshold = ${lookup mysql{SELECT quotawarn FROM users WHERE
username='$local_part' AND domainname='$domain'}{$value}{80%}}
quota_warn_message = "\
To: $local_part@$domain\n\
Subject: Your mailbox at $domain\n\n\
This message is automatically created by the mail delivery software\n\
at $domain.\n\n\
The size of your mailbox has exceeded a warning threshold that is\n\
set by the system administrator. Please remove mails from your\n\
mailbox in order to avoid possible rejection of incoming mail.\n\n\
Feel free to contact our tech support if you encounter any problems.\n\n\
----------------------------------------------------------------\n\n\"

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