[Help plz]Can't set a boolean attribute to true or false

Hello,

I'm new in NWDS development. I need to develop a download functionality

I used a FileDownload UIElement for that and I created a node context (ExcelExport) with 3 attributes :

- ExcelFile

- ExcelIcon

- And ExcelEnabled (Boolean type)

My problem is that everytime I try to set the attribute ExcelEnabled to true or false, it return me a java.lang.NullPointerException

I'm binding this attribute with "Enabled" property of the UIElement.

Have anyone got this error before? Thanks a lot for your help.

Kind regards,

Safae.