Error in SPIP Forum

Hello,
Warning! Your message needs to be at least ten characters in length
I give above error even when I post a Farsi message with more than 10 characters and even a paragraph with more than 50. I do not give any error when I post a message with English characters.
Farsi is a right to left language like Arabic with many same characters.
I use SPIP 2.0.6 [13835].
Is there anyone who can help me to fix it?
Regards
Kamran