RAF play with multiple ads

I am working on roku app using scene graph component, Implemented RAF in my app. I want to play multiple ads using RAF but it playing only one ad at a time Please provide suggestion to resolve it.
code -
adUrls = “http://fusioniprojects.com/rnd/addpod/adpods.php
m.adIface.setAdUrl(adUrls)
adPods = m.adIface.getAds()

I don’t know any issue of my VAST tag ?