Be sure you partitioned the disk using GUID and formatted it Mac OS Extended, Journaled. Here's someone's solution for a similar problem with El Capitan:
[From a reply by quizhelper (to staceybeee)}
Greetings staceybeee,
I'm sorry to hear that you're having an issue with downloading OS X El Capitan. I was actually able to resolve this issue.
I opened up the console and received an error command about a file being found in /var/folders/rz/XXXXX-XXXXXX/C/com.apple.appstore/
I opened up Finder > Go > Go to Folder and typed in /var/folders/ and went into RZ went into the file name which was replaced by X and I took that com.apple.appstore folder and pushed it into the trash can. I was immediately able to use the App Store and download OS X El Capitan.
You might see if it can help you. You may wish to Report a problem with item purchased from iTunes Store, App Store, or iBooks Store. Be sure you have no other OS X installer file on your disk. If you do then drag it to the Trash (don't Empty it, though.) Quit the App Store if it is open, then restart it and try again.
Another thing you can try is to repair the disk drive and permissions:
Repair the Hard Drive and Permissions
Boot from your Snow Leopard Installer disc. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities menu. After Disk Utility loads select the out-dented entry (mfgr.'s ID and disk size) from the the left side list. In the Disk Utility status area you will see an entry for the S.M.A.R.T. status of the hard drive. If it does not say "Verified" then the hard drive is failing or failed. (S.M.A.R.T. status is not reported on external Firewire or USB disks.) If the disk is "Verified" then select your OS X volume from the list on the left (indented entry, usually Macintosh HD,) click on the First Aid tab, then click on the Repair Disk button. If Disk Utility reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait for the process to finish, then quit Disk Utility and return to the installer.
If Disk Utility reports errors it cannot fix, then you will need Disk Warrior and/or Tech Tool Pro to repair the drive. If you don't have either of them or if neither of them can fix the drive, then you will need to reformat the drive and reinstall OS X.
[Permission to use part or all of the above has been granted by Kappy, exclusively, to theratter.]
