Moving from blogger to wordpress

Hello,

I am setting up a blog network. My clients have established blogs on the blogger platform and I am looking for an easy for for them to migrate otherwise it is a deal breaker.

I have installed the importation plugin, but when the test clients tried to migrate they got an error message:

'The page you requested cannot be displayed. Another site is requesting access to your google account but sent a malfomed request. Please contact the site you were trying to use before you got this error. A detailed error message follows:

The site http://domainname.com has not been registered'.

Please note that domainname.com is the mapped domain and not the sub-domain for the network.

Any ideas would be appreciated.