Electrostatic induction in a conductor

grantc

Two aluminium plates, each 150 x 150mm, were separated by 100mm to create a form of parallel-plate capacitor. A DC voltage of 300 volts was connected across the plates to create a (fairly) linear electric field of approximately 3000 V/m between them.
An insulated conductor was bent into a U shape with squared-off corners, with the bottom of the U approximately 95mm long and each leg of the U approximately 300mm long. This was placed between the abovementioned plates so that the bottom of the U was perpendicular to the centres of the plates, with the legs of the U adjacent and parallel to the inner surfaces of the plates.
Through electrostatic induction it was expected that about 300 volts would be measured across the legs of the U. However, there was no voltage seen, both on an oscilloscope and on a Fluke meter.
Similarly, when the plates were connected to a 50 Hz, 220 volt rms supply, there was no measurable voltage across the legs of the U.
What is the fallacy in my reasoning, please?