[imp] Can"t attach file that size greater than 2 MB.

[Somsak RAKTHAI]

Dear sir,
  I used horde-1.2.3 and imp-2.2.3. (old version.)
  I can"t attach file that size greater than 2MB.
It has error messages below when attach file.

Warning: Undefined variable: attachments_size in
  /usr/local/apache/htdocs/mail/compose.php3 on line 915

  Please let me know how to solve this problem.

          Thank you very much.
              regards,
              Somsak.