Textpattern errors after installing

I have tried to install Textpattern on my domain but after I go through the set up I get an error message:
“config.php is not ok or not found. If you want to install go to [subdir]/textpattern/setup/”

I look in my textpattern directory and config.php is there. If I go to www.mydomain.com it looks like Textpattern has installed properly, it is just when I try to go to the admin section (i.e. textpattern/index.php) I get the error message.

Has anyone run into this problem with Textpattern before? What am I missing?