path to plugin.ini for 'Contribution' is not correct?

When I go to install the "Contribution" plugin, I get the following error:

"The following error occurred while installing the 'Contribute' plugin: Path to plugin.ini for 'Contribution' is not correct."

The plugin.ini file is sitting at the top level of the plugins/Contribute directory which is the same place as all the other plugins that I'm using. Installing other plugins doesn't yield the same errors.

I'm using Omeka v. 1.0beta. Has anyone else experienced this problem or have any thoughts on what might be causing this error?