Getting a 404 error after using the WP import under tools. How can I resolve this issue?

I have Wordpress Multisite up, and I am looking at setting up my themes (using the Blog Templates Setup). I have a few themes, and thought of:
1) Setting up the theme
2) Install and activate req plugin
3) Import blog data (posts, pages etc)
3) Make a template out of it

Now I am stuck on the importing data part. It keeps giving me a 404 error after directing me to the blog URL.

I know you guys can help me on this! :wink: