InstallShield - How to run installer using custom actions (VB script)

Question

I have a package which binds my product and MATLAB run time as a dependency. The dependency should be installed only if its not present in target machine. I have selected deferred execution of a VB script (It should fire after File transfer).

Here's the code:

public function MatlabCheck()

Dim MATLABVal 
MATLABVal = Session.property("MATLABROOT")

If Len(MATLABVal) = 0 Then
   Set objShell = CreateObject("WScript.shell")
   Dim cmd
   cmd = Session.Property("INSTALLDIR\v1.0\dependencies\MCR_R2013b_win32_installer.exe")
   objShell.run cmd
end if

end function

Note that I have put MATLABROOT property under Additional Requirements.

Using InstallShield Limited Edition on VS 2013.

I tried running this setup with the script integrated, however, it didn't work.