Wordpress User Synchronization

Hello,

We just installed WPMU Wordpress User Sync on the "Sub site" with no problem (dev.mpsservices.be).

When I try to install it on the master site (www.mpsservices.be)... I have an error.

You can see it in attachment.

I just want to synchronize the users of mpsservices.be to our new wordpress (dev.mpsservices.be).

Could you fix that or tell me how I can do.

Thanks in advance.