Error when loading new assetbundle

Hello, I've a game in which I've a loader and 4 different cases. For each case I've assigned 3 bundles (1 for materials/textures, 1 for prefabs and objects, and one for the scene). Loading each one individually works perfectly. I tried inserting a kind of a navigation system to go from case 1 to case 2, but that gives me a weird error. Firstly, I load the scene depending on which case was chosen, then I check if cases variable has been changed. if so, I Unload(false) the current bundle and load the new. When the game is about to download the next bundle I get this error:-

 uncaught exception: abort(84) at jsStackTrace@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:22814
 stackTrace@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:22997
 abort@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:36:51345
 b4m@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:29:1
 hga@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:22:1
 t1@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:19:1
 rRl@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:15:1
 gqk@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:6:1
 J4g@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:13:1
 _ol@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:15:1
 A1m@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:29:1
 invoke_iiii@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:365872
 FJ@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:19:1
 Ev@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:19:1
 zvb@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:17:1
 EUb@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:21:1
 jRb@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:21:1
 iRb@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:21:1
 rmb@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:17:1
 L9a@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:14:1
 XOb@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:21:1
 F0e@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:20:1
 d1m@blob:http://dev.robogarden.ca/613b932f-ef60-4caa-bd44-e7de7d0af154:29:1
 Runtime.dynCall@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:6885
 Browser_mainLoop_runner/<@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:208149
 Browser.mainLoop.runIter@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:239269
 Browser_mainLoop_runner@blob:http://dev.robogarden.ca/1c7567f4-92d0-42b9-8368-f8e60b532949:1:208045
 
 If this abort() is unexpected, build with -s ASSERTIONS=1 which can give more information.

Thanks in Advance !