JavaScript - radio button validation

[sunsolaris2000]

A list of courses is displayed and user has to select 1, so I used radio buttons. The course list vary from one student to another.

If I have more than 1 courses displayed and user selects one, everything is ok, but if I display 1 course, the test is JS seems to not be right...

Validate if radio button(a course) was checked:

function validate2() {
				//validate radio buttons(if a course is selected)
				var n = document.entry2.courses.length;
				ok = 0;
				
				for(var i = 0; i < n; i++){
					if(document.entry2.courses[i].checked){
						ok++;
						break;
					}
				}			
				
				if((document.entry2.ex.checked == true)||
				  (document.entry2.sem.checked == true)||
				  (document.entry2.lab.checked == true)||
				  (document.entry2.pro.checked == true)){
					ok++;
				}
				
				if(ok == 2){
					return true;
				}else{
					alert("Please select 1 course and at least 1 activity! ok=" +ok);
					return false;
				}				
            }

<form action="Result.jsp" method="post" name="entry2" onSubmit = "return validate2()">
			      
			      Please choose a course from the ones
			      <br> where student is assigned:<br><br>
			      
			   ...............
			     
			    <table border="1" cellspacing="1" cellpadding="8" bgcolor= #EBDDE2> 
		
			 	<%
			 	Iterator<String> i = cs.iterator();
			    String sCourse = null;
			    
			 	while(i.hasNext()){
			 	  sCourse = i.next();	
				%>
				
				<tr>
				  <td><%= sCourse %><input type= "radio" name= "courses" value="<%= sCourse %>"></td>
				</tr>
				
				<%}%>
			</table>

ok is not becoming 1 at the for loop if there is 1 course only
Thank you!

[gits]

in case that this one option isn't 'checked' then it will not be counted - or what is the exact problem? can you post the html as it turns out in the browser instead of the jsp-page? may be you want to auto-select the option when there is only one available?

[sunsolaris2000]

ok must be 2 for the form to be submitted.
And I get ok=1 only when I have 1 course.