Are Amazon Earnings Really This Volatile?

I am having some really inexplicable results with Amazon. I installed an API script from AffilateBang on a handful of site in May 2010 and let it sit. I did not dare install it on more site because a few of my sites were subsequently banned by Google. These were my results


0 May 201
3.92
5.56
16.66
152.52
79.74
57.3
10.8
26.31 Jan 2011
0
0
15.21
0
211.43
309.27
234.9
156.29
126.32
381.55
531.15
65.96
0 Feb 2012

What happened was that there was a small burst of earnings at first, which peaked at $152.52 in Sep 2010. Then the earnings dropped to 0 and then suddenly restarted at $211.43 in June 2011. This peaked at $531.13 in Dec 2012 and then suddenly dropped rapidly to 0.

This cannot be explained by the drop in traffic nor by a usual drop in conversion rate after Christmas. I am worried that there may be something wrong with the script as Amazon said they were going to change their API in February. However, the script seems to work fine for me but perhaps my affiliate ID isn't being registered. The AffiliateBang site is down and so this make me more suspicious.

I wonder if anybody else has seen anything like this? I wonder if there is any other API script that you can recommend?

Derek