Photopress install

Hi,
I’m trying to install the photopress plugin, but I get the following error when I clicked on the Manage > Photopress tab. It showed up after I tried uploading a photo and now it stays there (the error message, that is)

photopress, Fatal error: Call to undefined function: attribute_escape()

I googled the error and found some web pages that had the error message on them, but no explination of how to fix it. Any direction would be much appreciated.

Thanks!