Thanks MR E for the reply!

pin 3 RA4, AN3 seems like it is an output because it is low impeadance.
I am trying to measure 0 - 4 vdc and have a 10k series
resistor and a .1uf capacitor. The voltage is loaded down
on some boards, a few boards pin 3 seems to work.
I figure I am missing some configuration setting or don't understand
something. 3 other adc inputs work as expected.

Mark