Op Amp not providing sufficient gain
Spehro's comment is almost certainly correct. Here is how you can check:







simulate this circuit &ndash; Schematic created using CircuitLab

Add R3 and R4 to your circuit, and the two voltages shown should match. Next, short R4 with a clip lead or a piece of wire, and the output should go to zero.

If it works in both cases, you're in business.