Failure to import CSV with ConvertFrom-Csv

I have a script that is designed to record the consumed data of all my virtual machines and create a CSV with the data.  The script checks for the existence of a file with the same name as the output  file and I attempt to set the file as an array so that I can add the next day's data.  I found that if the CSV only has one row of data the code   $csvreport=typeC:\Temp\DataGrowth.csv | ConvertFrom-Csv fails to import the file.  If I create a second row of data the code works perfectly.  Can anyone tell me why this is happening? 

This csv can be imported

"Collection_Date","Total_Size","VM_Count"

"6/25/2013","10","1487"

"6/25/2013","10","1487"

"6/25/2013","10","1487"

This CSV can not be imported

"Collection_Date","Total_Size","VM_Count"

"6/25/2013","10","1487"