Calling Feedburner

You there guys? You listening? Great – got a quick question for you. In your Feedburner stats, you’ve thoughtfully begun to aggregate people who’ve subscribed to different versions of my feed so that I have a better picture of my actual subscriber number. I love it. The problem is, it doesn’t always work all that well. Taking my Bloglines and NewsGator Online subscribers as an example: those numbers vacilate wildly as Feedburner appears to temporarily “lose” various segments of my subscriber base. I have, unfortunately, four different subscriber bases in Bloglines. Sometimes you track all four, sometimes three, sometime two, and rarely – only one. Depending on who’s lost – like the folks subscribing to feeds.feedburner.com/tecosystems, for example, my subscriber number swings up or down by 30, 40, 50 even 60 users in the space of a few hours. While I look carefully enough to not panic when I lose half my audience in this fashion, some of your users might not. Any idea what’s causing it? Would appreciate any insights, thanks.