Trying To Bind Vungle Ads Sdk [Solved]

I’m trying to use Vungle Ads Sdk in my moe libgdx project.
I’ve successfully implemented admob and unityads sdk, however, having a trouble with Vungle. The problem is that delegate callback methods seem not working though I added @selector annotations (this made it work in other sdks).

What should I be looking for in case of delegate callback problems?

This is how I initialize :
NSArray placements = NSArray.arrayWithObject(“DEFAULT04405”);
VungleSDK vungleSDK = VungleSDK.alloc().init();
Ptr ptr = PtrFactory.newObjectPtr(NSError.class, 1, true,true);
NSError nsError = null;
if(!vungleSDK.startWithAppIdPlacementsError(“59a7eb387fd978c408003fb6”, placements, ptr))
System.out.println("failed "+ptr.get().description());

I solved the issue just after posting, the problem is the order of method calls, my bad. Thanks