Wien bridge oscillator LTSPICE
Even though this question may be solved, I ran into this sort of problem when trying to simulate the Wien bridge oscillator. 

Using LTSPICE:


The voltage gain of the amplifier circuit MUST be equal too or greater than 3 for oscillations to start because the input is 1/3 of the output. This value, ( Av ≥ 3 ) is set by the feedback resistor network.
Since oscillators start up from thermal noise you may need to provide an initial pulse input for the simulation to get going.


The following steps enabled me to successfully simulate this oscillator without an initial pulse input on Proteus Software.

Using Proteus:


Step 1 above applies.
Proteus simulation software does not require this initial 'push' and thus it may be easier to use Proteus software.
Make sure to use active capacitors while simulating, otherwise nothing will happen.