Tax revelation

My business got stiffed for $4300.00 by a company that quit paying it's bills! Government says "if you havn't paid tax on the earnings, then you can't claim the loss". Situation is that the customer was only active during the tax year. Bottom line, is you do all the work for the folks, then they stiff you, and you can't claim anything as a loss. Just does'nt seem fair. Especially since the tax rate for self employed folks is just about 33% of AGI. But, you can't deduct any of the above.