SharePoint PowerShell Create Site

Some days ago, i had installed a SharePoint 2010 on Windows 7, but there are very strange, i can create webapplication, but i can not create top level site in this webapplication; there are always throw an Error like this:

Cannot complete this action.

Please try again.

a couple of days i just busy on work, and this days, i tried to create site use SharePoint PowerShell, use default web template and i created successful. the code like this:

PS C:\Users\YourUserName> New-SPSite -Url "http://CHDLDev004L:20000/sites/NewSense001" - owneralias "Domain\UserName" -Name "NewSense001" -Template $template

cheers, and i guess that i can not create site from SharePoint UI because that my iis has some incurrect configuration.