Posted on: June 11, 2012, 12:22:25 AM
It could be a couple of things.
I know you say you are using the 1.5 version but, just to be sure, you are trying to install the bare template and not the siteshaper?
Have you tried downloading the template again? Sometimes a corrupt download will give this error.
Check Global Config > Server > Path to tmp folder. Try making it just /tmp if it isn't already.
Make sure you have the correct permissions on your folders.
If all else fails, try unzipping the download and uploading the files to your tmp folder. Then in the extension manager, use the optio to install from a folder on the server.