Historical data in Graphite, Whisper files always show None

I have been struggling with this for waaay too long now. Trying to get the carbon/graphite/grafana combo to work. My app is a backtesting application that plays years of historical data, and there is a single stat being reported per historical day. I see the whisper files getting created under /opt/graphite/storage/whisper/ but when I do a whisper-fetch.py --pretty *.wsp, I only see entries with None in them. My storage schema looks like this:
[carbon]
pattern = ^carbon\.
retentions = 60:90d

[default_1min_for_1day]
pattern = .*
retentions = 60:90d

I don't need any aggregation, all I want to do is display the data that I am sending to graphite as is.