Problem with Wien's Bridge basic working and simulation in multisim
From memory (meaning it's a long time since I used them) you need a gain of 3 for the Wien bridge to oscillate, and you have lower gain than that : 1 + R6/R3 gives a gain of around 1.2. If you reduce R4 far enough (to about 5k) it ought to start oscillating.

This page shows a better way to set the gain (scroll down to "non-inverting amplifier").

As for why you need a gain of 3 - work out the impedance of the series arm (RC in series) at the resonant frequency : you'll find it's sqrt(2) * the resistor. Now work out the resistance of the shunt arm (RC in parallel) - it's R/sqrt(2). Thus the input voltage is 1/3 of the output voltage meaning you need a gain of 3 to sustain the oscillation.