Paypal Standard

Dave I have this in my Paypal form,

<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="MyClientUser">
<input type="hidden" name="item_name" value="<?php echo htmlspecialchars($record['nombre']); ?>"/>
<input type="hidden" name="amount" value="<?php echo htmlspecialchars($record['precio']); ?>"/>
<input type="hidden" name="no_shipping" value="0"> <input type="hidden" name="logo_custom" value="https://www.worldwidetrainings.com/images/buttons/inscribir_el.jpg">
<input type="hidden" name="no_note" value="1"> <input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="lc" value="US"> <input type="hidden" name="bn" value="PP-BuyNowBF">
<input name="submit" type="image" src="MyclientButton" alt="PayPal - The safer, easier way to pay online!" align="absmiddle" border="0">
<img alt="" border="0" src="https://www.paypal.com/es_XC/i/scr/pixel.gif" width="1" height="1">
</form>

When I click on the button Paypal page says:

Error in Price Format

I think I doing bad the next step:

<input type="hidden" name="item_name" value="<?php echo htmlspecialchars($record['nombre']); ?>"/>
<input type="hidden" name="amount" value="<?php echo htmlspecialchars($record['precio']); ?>"/>

I have to put another type of code, but I do not know which one.

Thank you, Juan.