Why Is My Physical Pendulum Period Calculation Incorrect?

[lc99]

Homework Statement

Homework Equations

T = sqrt(mgL/I)

The Attempt at a Solution

my calculated Inertia (I) = 1/3(m/2)L^2 + (m/2)L^2
my distance (d) = L/2
m is just total mass

so, T = 2pi * sqrt(mgd/I) = 2pi sqrt(4L/(3g)) which is wrong :(

 

[PumpkinCougar95]

The time period is Given by: $$ T = 2\pi \sqrt{ \frac { I \theta } { \tau } }$$
Also Where is the Center of mass? Are you sure it is at $\frac {L} {2}$. Take the torque about that.