I just tested your newest interstitial SDK

java.lang.StringIndexOutOfBoundsException: length=0; regionStart=316449504; regionLength=-1591054304
at java.lang.String.startEndAndLength(String.java:298)
at java.lang.String.codePointCount(String.java:1471)
at com.appnext.ads.interstitial.Interstitial$1.run(Interstitial.java:89)
at java.lang.Thread.run(Thread.java:818)

It´s getting more and more impressive how obvious you release buggy software and don't care about it.