Wrong e-commerce report!

This is our ga code for e-commerce, the report total revenue sometimes is about double of the real revenue, sometimes is about half of the real revenue.....

<!-- Google Code for Purchase Conversion Page -->
<script type="text/javascript">
<!--
var google_conversion_id = 1021819549;
var google_conversion_language = "en";
var google_conversion_format = "2";
var google_conversion_color = "ffffff";
var google_conversion_label = "AkY_CK2apwEQnaWe5wM";
var google_conversion_value = 0;
//-->
</script>
<script type="text/javascript" src="http://www.googleadservices.com/pagead/conversion.js">
</script>
<noscript>
<div style="display:inline;">
<img height="1" width="1" style="border-style:none;" alt="" src="http://www.googleadservices.com/pagead/conversion/1021819549/?label=AkY_CK2apwEQnaWe5wM&guid=ON&script=0"/>
</div>
</noscript>


<!-- Google Code for Pay/Sale Conversion Page -->
<script type="text/javascript">
<!--
var google_conversion_id = 1033245377;
var google_conversion_language = "en_US";
var google_conversion_format = "1";
var google_conversion_color = "ffffff";
var google_conversion_label = "-FuWCMfygQEQwaXY7AM";
var google_conversion_value = 0;
//-->
</script>
<script type="text/javascript" src="http://www.googleadservices.com/pagead/conversion.js"> </script>
<noscript><div style="display:inline;"><img height="1" width="1" style="border-style:none;" alt="" src="http://www.googleadservices.com/pagead/conversion/1033245377/?label=-FuWCMfygQEQwaXY7AM&guid=ON&script=0"/> </div></noscript>



<!-- Google Code for purchase/sale Conversion Page -->
<script type="text/javascript">
<!--
var google_conversion_id = 1021480914;
var google_conversion_language = "en";
var google_conversion_format = "2";
var google_conversion_color = "ffffff";
var google_conversion_label = "NhysCOaVeQEQ4u2K5wM";
var google_conversion_value = 0;
//-->
</script>
<script type="text/javascript" src="http://www.googleadservices.com/pagead/conversion.js">
</script>
<noscript>
<div style="display:inline;">
<img height="1" width="1" style="border-style:none;" alt="" src="http://www.googleadservices.com/pagead/conversion/1021480914/?label=NhysCOaVeQEQ4u2K5wM&guid=ON&script=0"/>
</div>
</noscript>

May anyone can tell me the reason, it really make me crazy.....

 

Did you implement this on the Receipt page of your ecommerce platfomr? How are you passing the values in GA?

 

I put the code before paypal page......so, the data is incorrect, but the thing is, why sometimes is double and sometimes is half?