Cascaded Voltage Divider

I have the following circuit:

^{simulate this circuit– Schematic created using CircuitLab}

At first glance, it looks like the expression for the voltage at V0 is the following:

$$ V_0 = \left(\frac{R_2}{R_1+R_2}\right) \left(\frac{R_4}{R_3+R_4} \right)V_1 \tag{1}$$

This is incorrect and the voltage is actually the following:

$$ V_0 = \left(\frac{R_2||(R_3+R_4)}{R_1+R_2||(R_3+R_4)}\right) \left(\frac{R_4}{R_3+R_4} \right)V_1 \tag{2}$$

Why is the first equation incorrect? I'm just a little confused.