Alex, Looks like we've found out what could be a problem:
Log message editing is not enabled by default. To allow such changes you need to create pre-revprop-change hook. Here is detailed description of this hook: http://www.visualsvn.com/support/svnbook/ref/reposhooks/pre-revprop-change/. For your case it can contains the only line exit 0. To add a hook please select Properties->Hooks command from the context menu of the repository in the VisualSVN Server Manager and select the hook file you would like to add/edit. Hope this helps! -- Regards, Olga Dolidze VisualSVN Support