Can't Unset readonly attribute of a textbox

i need to make a textbox in html readonly and not readonly based on certain choices

if(PaperName=='Examiner')
{
document.getElementById('Papername').readOnly="True";
}
else
{
document.getElementById('Papername').readOnly="False";
}

The problem is that once the readonly attribute is set to true it does not seem to unset to false.

use DOM

var obj =document.getElementById('Papername');
if(PaperName=='Examiner')
{
obj.setAttribute('readOnly','readonly');
}
else
{
obj.removeAttribute('readOnly');
}

Works like a dream. THANK YOU!

i need to make a textbox in html readonly and not readonly based on certain choices

if(PaperName=='Examiner')
{
document.getElementById('Papername').readOnly="True";
}
else
{
document.getElementById('Papername').readOnly="False";
}

The problem is that once the readonly attribute is set to true it does not seem to unset to false.The reason this doesn't work is because the property must be passed a boolean (true or false) not a string. The string "True" evaluates to true but so does the string "False".