About pre-revprop-change

I'm a biginner of SVN in Japan,
I want to change the past log-message, but I got an error from SVN like 'Ask your administrator to create the hook of pre-revprop-change'.
But there is no information about it in my manual and I have no idea about the administrator it's mentioned.
Could someone teach me the way to change the log message or change past log-message ?

Thank you in advance and best regards.

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