How to set a DFF Text value in OAF

Hello,

New to OAF, try to get a DFF value in OAF Controller extension for checkoutSummary page, try to get the value of Attribute15 in the page, so that I could perform validations and write back the new custom value. But I am not getting the values, Please Suggest.

Code Start
==========
        OADescriptiveFlexBean dff = (OADescriptiveFlexBean)webBean.findChildRecursive("ReqHeaderDFF");
        if (dff != null) {
            System.out.println("1. Value of DFF Bin is  "+dff.toString());  
        }
        else {
            System.out.println("1. No flex ID found  ");  
        }
       

OAWebBean dffbean = (OAWebBean)dff.findChildRecursive("ReqHeaderDFF14");
        if (dffbean != null) {
            System.out.println("2. Value of DFF Field is  "+dffbean.toString());  
        }
        else {
            System.out.println("2. No flex value found  ");