changing site name

Hi,
I have been trying to change my single site name(site url as well) but I could not manage it.
In SPSite there is Rename method but it fails it says it could be renamed if it is host named site.
Then I have tried to backup and restore into deifferent url but in visual studio I am getting access denied error:
System.Security.SecurityException was unhandled by user code
   at Microsoft.SharePoint.Administration.SPSiteCollection.VerifyCurrentUserIsAdministrator()
   at Microsoft.SharePoint.Administration.SPSiteCollection.Restore(String strSiteUrl, String strFilename, Boolean bOverwrite, Boolean bGradualDelete, Boolean hostHeaderAsSiteName)
   at Microsoft.SharePoint.Administration.SPSiteCollection.Restore(String strSiteUrl, String strFilename, Boolean bOverwrite, Boolean hostHeaderAsSiteName)
   at FootFall.Redef.Services.Core.SharePointEngine.<>c__DisplayClass3.b__0()
   at Microsoft.SharePoint.SPSecurity.<>c__DisplayClass4.b__2()
   at Microsoft.SharePoint.Utilities.SecurityContext.RunAsProcess(CodeToRunElevated secureCode)
I have tried to see what the problem is so I have tried with sharepoint management shell if I try to restore into different url it gives me content database error:It syas either content database doesn't exist or no space for the site but if I try to restore for the same url it finishes it.


Could you please help me to solve this because I need to keep all existing themes,web parts, excel services,report files when I change the site name and url?
Kind Regards
Reside Ozsoy
Software developer