Help Please. No themes Displaying

I've been successfull installing Elgg 1.7.1 but after installation there is no default theme displaying. I also cannot install a new theme. I get the same problem I've read about (but haven't seen an answer to yet) where when I add a theme to my mod folder and then go to enable it, there is no enable button. I've checked to make sure my paths are correct and they are. Any suggestions on how to get this fixed.