Exporting Distribution Group Members

I am trying to run the following script but it gives me a message about Input being NULL.  What am I missing?

$report=foreach($i in Get-DistributionGroup | where {$_.Name -like '*equity*'}) {

  Get-DistributionGroupMember $i -ResultSize Unlimited |

    Select-Object @{n="Member";e={$_.Name}},

       @{n="Group";e={$i.Name}}

}

$report | Export-CSV c:\GroupMembers.csv -NoType