Conditional button display in OAF 12.1.3

I have a custom page and in it I have a button - it is working fine

I now want to enable/disable (or hide/display) the button based on a condition. A value in one of the fileds

SO:

I added another ViewAttribute to the VO

typed Boolean (not the boolean - the Java.lang.Boolean)

3. I set the render of the button to SPEL and set the value to $oa.MyVO.DisplayFlag

4. I added the setting of the new field in the setter of one of the DB based

it looks like

...

if "red".equals(getAttributeInternal(COLOR))

setAttribute("DisplayFlag",Java.lang.Boolean.TRUE)