Need to read value of input field from iFrame

[Winpygsfli]

I have an application that has an iFrame wich houses a form. I need to read the value of a specific input field from the iFrame.

iFrame - portalArea
Form - frmUserProfile
Input field - logonName

Sample

alert(window.frames['portalArea'].document.forms['frmUserProfile'].elements['logonName'].value);
 

It keeps telling 'value' is null or not an obeject, but it has text in it. Please show me the err of my ways.

[Logician]

Frame - portalArea
Form - frmUserProfile
Input field - logonName

Without the page code it's pure speculation. One or more of the above is an ID instead of a name, or the element is being addressed prior to being rendered.