ClientException : is too old

hi all,
i am running eclipse(64bit) on windows7(64bit). i installed subclipse 1.8 plugin in that eclipse. i installed silk svn 1.6.16(64 bit). when i open svn item in preferences window in my eclipse the item shown in svn interface client is JavaHL 1.7.2 which is different from 1.6.16. when i try to do any of the svn related command from eclipse it throwing error
"org.apache.subversion.javahl.ClientException: The working copy needs to be upgraded
svn: Working copy 'E:\myworkspace\contactmanager\com\super\system' is too old (format 10, created by Subversion 1.6)"

thanks any help is appreciated.
auhuman