Rich TextBox is not auto populating as SharePoint list field

Hi Folks,

I got a task in which i need to auto populate custom list fields from another list.I am explaining my requirement. I have two lists name Project and ReuseProject. I need to fetch data from Project.On the NewForm.aspx page of ReuseProject List i need to auto populate list fields when  user enters ProjectID .To do so i used javascript and CAML Query and register onchange event for ProjectID text field.It works fine but,my problem is, it is populating all the field(Which are TEXT field,using document.getelementById fields are mapped) except one field which is RICH TEXT BOX. Even my Query is correct ,i am getting value for Rich Text Box but is not populating data.Also, i need to make RICH TEXT BOX as ReadOnly.

Thanks in anticipation!!!

Keshav Roy