FDC 1004 EVM and reference sensor

I am working an idea using the FDC 1004. I have the EVM hooked up and reading information. I have also had a sensor made similar to the reference design sensor. The only real difference is moving the connections to the top of the sensor instead of the bottom.  When working with the EVM I can register up to 16pf of capacitance by placing a finger over the right or left pad on the EVM.  When I place the manufactured sensor into liquid, the most I can measure is ~3pf.  even placing a hand over the sensor areas doesn't produce the same level of measured capacitance.  Is this expected behavior? I am hoping to utilize the sensor as a means of measuring the density of the liquid... the sensor would float enclosed in the liquid and move up and down relative to the density.  The reference sensor design appeared to be perfect for the usage, but I would like to have more measured capacitance to work out a higher resolution in change.