Mayfly and Maxbotix MB7386 Range Issue

I am still trying to get a water level sensor together. I got the code, radios, and Ethernet connection all working. I am able to get the data posted to a MySQL database. Now I am havin

I am still trying to get a water level sensor together. I got the code, radios, and Ethernet connection all working. I am able to get the data posted to a MySQL database. Now I am having range issues. The MB7386 should detect objects about 30 feet away. The most I am able to get is 15 feet to a cinder block wall. I am using the v0.3 mayfly, supplying 4.3 volts to the board. I have contacted Maxbotix. They recommended trying different objects. I did that, but still no luck. The readings I am getting are accurate, so it isn’t a units issue in the code. I’m reading everything in mm. This is what the sensor outputs.

Any help is greatly appreciated.

Thanks

Scott