Problem installing EasyBlog

I have just purchased EasyBlog for 2.5 Joomla! but am having problems installing it. I'm trying to install it through the extension manager but I keep getting a message telling me that that "there is an error uploading to the server". Firstly the file size is within the limit, it's only 5 MB, I believe you are allowed to upload to a maximum of 10 MB within file manager. I have downloaded the correct EasyBlog package so I know that is not the problem. Also, I've tried a couple of Joomla! 2.5 websites and it won't install on either. I've also tried using a couple of computers, still no luck, so I can rule out the problem with the website. Any ideas would be much appreciated!