Parallel->Series switches for capacitor bank, only one charges
You are using your transistors incorrectly. In fact, I think that the only transistor which behaves as a switch in your circuit is T2.

Note that a transistor, NMOS for example, will conduct while \$V_{GS}&gt;V_T\$. You are biasing your NMOS transistors in such a way that the potentials at source terminals is much higher than at gate terminals.

I believe that the reason you see a constant voltage on the load is because T3 and T4 are conducting when \$VG_2=5V\$, and T1 and T5 are conducting when \$VG_2=-5V\$ (in all cases due to wrong biasing). You can easily check my guesses in simulation by measuring the currents.

Furthermore, take a look at transistors' datasheets - the voltages in your circuit exceed the max ratings for the transistors.

The component you are trying to implement is called "Charge Pump" - there are many standard implementations you can find on the internet. A short (but not complete) overview may be found here.