Error when searching for a well known plugin

Hi Im in the middle of building a brand new website for someone and already added some plugins but just now went to search for a plugin (Yoast) and it came up with this message:
“An unexpected error occurred. Something may be wrong with www.remarpro.com or this server’s configuration. If you continue to have problems, please try the support forums”.
My other website finds it fine. They are both with hostgator, but my one is under a different name to theirs so not both on the same one.
Any ideas? Thanks, Jo ??