Creating a new website

Im trying to create a website in IIS, an app-pool, and the location where the site files are stored along with the binding using this script:

Import-Module WebAdministration
New-Item -type directory -path D:\testsite
New-Website -Name "testsite" -bindings @{protocol="http";bindingInformation=":80:TestSite"} -Port 80 -IPAddress "192.168.1.99" -PhysicalPath D:\testsite -ApplicationPool "ASP.NET v4.0"

 but i get the error "a parameter cannot be found that matches bindings"

whats going wrong here?