Why can´t I see the AMOUNT field when I create an opportunity when converting a possible client to customer?

Why can´t I see the AMOUNT field when I create an opportunity when converting a possible client to customer?

Hi,
I am having problems when coverting possible clients to customers and creating opportunities inmediately in the same process. The system doesn´t show me the AMOUNT field in this process.  How can include this important field in this part of the conversion process?

Thanks for  your advice.