Import IIS configuration csv for Add-WindowsFeature with alternate Source on Win2012r2

I've been given an export csv of a webserver IIS configuration to apply to a new server. I've mounted the win2012r2 installation material to E:\sources\sxs. 

Running 

Import-CSV C:\TEMP\ecp-jc-stssrs01_webfeatures.csv | foreach{Install-WindowsFeature -Source "e:\sources\sxs" $_.name -Whatif}

Getting

WARNING: Files for some of the features are not available on the target server. You may need to specify an alternate s
ource path for missing feature files by adding the -Source parameter. If a path is not specified, by default, the comm
and attempts to use a Group Policy setting or Windows Update to find the files.

It doesn't seem to be picking up the -Source parameter.

Suggestions appreciated. Thanks!