Unexpected result of document.getElementById.value?

When I run the following code:

document.getElementById('somevar').value = '25';
alert(document.getElementById('somevar').value );

"somevar" is displayed, instead of 25. Why is this? Thanks in advance for any help.

EDIT: input type of 'somevar'is hidden

I suspect this is happening because when you run the code the element you're trying to access is not yet ready. Make sure you run your code after the DOM has loaded by using onload for plain javascript or the ready event if using jQuery.

As show on my fiddle, if an element is defined with the right name, it show the correct result:

http://jsfiddle.net/Achilleterzo/kcp2n/

It should work. Here is a sample on JsFiddle