Error while getting libraries name using powershell script

I am executing the below script to get all libraries name in subsite:

Get-SPweb http://server:80/sites/sitename/subsitename |
   Select -ExpandProperty Lists |
   Where { $_.GetType().Name -eq "SPDocumentLibrary" } |
    Select Title

I am getting error: Cannot find an SPWeb object with id or url :......