Hi i found these 2 things that maby can help:
1. Go to Disk Utility and open it
/Applications/Utilities/
2. Select the main disk. Not the disk where OS X Snow Leopard is installed on
3. Go to Partition
4. Make the Machingtosh HD Partition 1 GB Smaller (or 128 MB)
5. Click Apply
6. Start the OS X Lion instalation again.
i found this on the Apple support page for more info go to:
http://support.apple.com/kb/TS3926
or you can do this
ds store
Create a Backup Lion Bootable 10.7 Disk
Purchaseand download Lion from the Mac App Store on any Lion compatible Macrunning Snow Leopard.
- Right click on “Mac OS X Lion” installer and choose the option to “Show Package Contents.”
- Inside the Contents folder that appears you will find a SharedSupport folder and inside the SharedSupport folder you will find the “InstallESD.dmg.” This is the Lion boot disc image we have all been waiting for.
- Copy “InstallESD.dmg” to another folder like the Desktop.
- Launch Disk Utility and click the burn button.
- Select the copied “InstallESD.dmg” as the image to burn, insert a standard sized 4.7 GB DVD, and wait for your new Lion Boot Disc to come out toasty hot.
With this disc you can boot any Lion compatible Mac, and install10.7 just like you installed previous version of Mac OS X. You caneven use Disk Utility's Restore function to image your Lion boot discimage onto a external drive suitable for performing a clean installon a optical-drive-less MacBook Air, or Mac mini server.
If your using Mac's in a mission critical type environment or have third party hardware or software you must rely upon working correctly. It's advised to wait until all the bugs, driver updates, third party software updates and other issues are resolved before upgrading. This might take several months. Then if you do so, do one machine at a time and carefully test everything before full deployment.
It's also highly advised to backup all one's data either manually to a external powered drive in addition to TimeMachine and Hold option bootable Carbon Copy Clones etc.