Build shipping modules without tax_class_id

Hi:
I'm trying to build a new shipping module for my country and area. Because this shipping company only works in the country Tax are not applied to any product and prices depends on weight. Anyway I don't want to use tax_class. The modules are programmed but because no one use Taxes and then this error appear:

Notice: Undefined index: tax_class_id in D:\Webserver\htdocs\libnew\catalog\model\total\shipping.php on line 14Notice: Undefined index: tax_class_id in D:\Webserver\htdocs\libnew\catalog\model\total\shipping.php on line 14

How I can fix this?
Cheers and thanks in advance

Have you tried building in the tax_class_id but setting it to 0?

Thanks it works now perfectly :)