Can't join Session [Advanced Session Plugin with Steam]

Hi,
I have this Problem for quite a while already trying to find the solution for the Problem on the Internet didn’t help.

I Create a Session with the “Advanced Session Plugin” (with Steam) and after that I want to join that Session.
I do find the Server / Session in the Server Browser but when I want to join that Session the Game crashes.
The odd thing is that the “Join Session” Node gives me a “Joined Successfully” in the log.

I am clueless to be honest. I tried a to create and join a local session, this works without any problems. I am testing this Issue with two different clients in different Networks with different Steam Accounts / Clients.

Create Session:

https://my-run.de/downloads/s/schlumpf_05_03_16_b7j3e.png

Join Session:

https://my-run.de/downloads/s/schlumpf_05_03_16_bf3dr.png

Some Line from the Log:
[2016.05.03-20.09.57:705][247]LogBlueprintUserMessages: [SearchGame_C_0] 0 // this is the Session ID
[2016.05.03-20.09.57:706][247]LogBlueprintUserMessages: [SearchGame_C_0] Joining Session…
[2016.05.03-20.09.58:017][267]LogBlueprintUserMessages: [SearchGame_C_0] Joined! // Joining Node returned Success then it crashes

Full Log:

Someone is wrong with your net driver definitions it is erroring out at the end because it is failing to create the net driver:

// Try to create network driver.
		if (GEngine->CreateNamedNetDriver(this, NAME_PendingNetDriver, NAME_GameNetDriver))
		{
			NetDriver = GEngine->FindNamedNetDriver(this, NAME_PendingNetDriver);
		}
		check(NetDriver); <- This is where it is throwing the fatal error

It might have something to do with the fact that you have a misspelling in your net driver definitions as the log also states at the beginning, try removing the extra character in DriverClassNameFallback=:

[2016.05.03-20.09.53:055][  0]Warning: Unknown property in NetDriverDefinition: DriverClassNameFall?back="OnlineSubsystemUtils.IpNetDriver")
[2016.05.03-20.09.53:130][  0]LogSlate: SlateFontCache - WITH_FREETYPE: 1, WITH_HARFBUZZ: 1
[2016.05.03-20.09.53:130][  0]LogSlate: SlateFontCache - WITH_FREETYPE: 1, WITH_HARFBUZZ: 1
[2016.05.03-20.09.53:171][  0]LogWindowsMoviePlayer: Unable to load movie: ../../../Grow411/Content/Movies/Default_Startup.mp4
[2016.05.03-20.09.53:203][  0]LogHMD: Failed to initialize OpenVR with code 110
[2016.05.03-20.09.53:207][  0]LogUObjectArray: 25032 objects as part of root set at end of initial load.
[2016.05.03-20.09.53:207][  0]LogUObjectAllocator: 5222728 out of 0 bytes used by permanent object pool.
[2016.05.03-20.09.53:207][  0]LogUObjectArray: CloseDisregardForGC: 0/0 objects in disregard for GC pool
[2016.05.03-20.09.53:218][  0]LogEngine: Initializing Engine...
[2016.05.03-20.09.53:229][  0]Warning: Unknown property in NetDriverDefinition: DriverClassNameFall?back="OnlineSubsystemUtils.IpNetDriver")

That was really it! Thank you so much, i really appreciate it.