VirtualBox extension pack error

I purchased a network card to give a separate network to my virtual machine. My host OS is Ubuntu 14.04 . Also i need to mount the USB to my virtual machine and not my host OS, so i downloaded extension pack version 5.0.2 for Vbox-5.0 . While installing virtual box extension pack, there were two VM's running and i got this popup.

Failed to install the Extension Pack /home/aniket/Downloads/Oracle_VM_VirtualBox_Extension_Pack-5.0.20-106931.vbox-extpack.

Failed to load the main module ('/usr/lib/virtualbox/ExtensionPacks/Oracle_VM_VirtualBox_Extension_Pack/linux.amd64/VBoxPuelMain.so'): VERR_FILE_NOT_FOUND - /usr/lib/virtualbox/ExtensionPacks/Oracle_VM_VirtualBox_Extension_Pack/linux.amd64/VBoxPuelMain.so: undefined symbol: RTLogRelGetDefaultInstanceEx.

Result Code: NS_ERROR_FAILURE (0x80004005)
Component: ExtPackManager
Interface: IExtPackManager {3295e6ce-b051-47b2-9514-2c588bfe7554}

Even after power off of VM's and restarting the host OS, I get this similar error code.

Sorry if you think the question is not formatted properly or any other issue with my question. This is my second post, please tell me if there are any things i need to correct in my question.

Thanks in Advance.

After lot of test and trial, the solution I found that the extension pack was not compatible and hence I had to download the compatible version of the virtualbox I am running on.

What happened was this, I was running virtualbox-5.0 and the version I was trying to install was 5.0.20 .

You can check your version by clicking on Help and then About Virtualbox and download the exact compatible extension pack, else it will through the same hex error code 0x80004005 which means file not found.