Junos Pulse not installing correctly on Yosemite
The way Juniper does this is a little confusing. Installing the JuniperSetupClientInstaller.mpkg installer from a Junos Pulse VPN server essentially sets up your machine so that the VPN server can then proceed to install Pulse using a Java applet. Here's how the install process works for my shop's Junos Pulse VPN server.


Open Firefox
Go to the following site:


https://vpn.server.goes.here


Log in with your VPN credentials.
If prompted by Firefox, allow the Java applet from the VPN site to run.
If this is the first time that Junos Pulse has been installed on this Mac, you may be prompted to install the Juniper setup client. If you are not prompted, go to step 6.


Click on the Please click here to install setup client link.
The Juniper setup client will be downloaded in a disk image file.
Double-click on the downloaded disk image file to get access to the Juniper setup client installer.
Double-click on the Juniper setup client installer and follow the prompts to run the installation process.
Once installation of the Juniper setup client has been completed, click on the Once the setup client is installed, please click here to continue link.

When prompted to install Junos Pulse, click the Always button.
The Junos Pulse installer will download to your Mac.
Once Junos Pulse has downloaded, the Junos Pulse VPN client will be installed on your Mac.
Once installation is finished, the Junos Pulse client will automatically connect to the VPN.


Everything in step #5, where the directions are having you install the Juniper setup client, is where the JuniperSetupClientInstaller.mpkg installer comes in. It's not the actual VPN installer; it's an installer that preps the machine for the later VPN client installation in steps 6 through 9. 

By itself, the JuniperSetupClientInstaller.mpkg installer will not install the Junos Pulse VPN client.