check bok error

hello everybody... I have a question, anyone can help me: I have a form in a html page: <HTML> <FORM METHOD=POST ACTION="test.asp"> <INPUT TYPE="checkbox" NAME="primero" value=4> op1 <INPUT TYPE="checkbox" NAME="segundo" value=5> op2 <INPUT TYPE="submit"> </FORM> </BODY> </HTML> this generate a form with two checkboxs and a button okey I have this program in php but it have a error: <?php echo $primero; ?> now the error is show, when I do not check on the first check box, but if I check it all is good. this is the message error: Warning: Undefined variable: primero in c:\inetpub\wwwroot\asp\test.php on line 2 help me please..... thanks in advance atte harold arando arandor@ucbcba.edu.bo