While trying to add an item to a SharePoint List, i had the following error message:
Unable to index into an object of type Microsoft.SharePoint.SPListItem. + $newItem[ <<<< "column_name"] = $SPFieldUserValue + CategoryInfo : InvalidOperation: (column_name:String) [], RuntimeException + FullyQualifiedErrorId : CannotIndex
Column name are case sensitive, and i had forgotten a caps !