Ensure that the route traces directly through the pads of all the filter capacitors and not by a stub route.
The following figure shows the correct way to route through a capacitor pad.
Figure 1. Correct Routing Through Capacitor Pad
The following figure shows a stub route to the capacitor pad. This must be
avoided, as it adds additional impedance in series with the capacitor. 
Figure 2. Incorrect Stub Route To
Capacitor Pad