After mentioning the DiffMerge as the  Diff Application in svnX preferences, I was receiving the below error message each time I tried to use the DiffMerge from SVNx.

The DiffMerge application was not able to be opened due to the non availability of file in the /usr/local/bin directory.

Copy the file from the’s  Resource folder  in to the bin by the following command:

cp /Applications/ /usr/local/bin/

If this throws you Permission Denied error,  run the command using sudo command.

Once the copy is done , the svnX application will be able to open DiffMerge app.