arduino and labview

hi everyone ,
in my projet i use the arduino for voltage aquisition toward the laptop.
when i make a constant resistance, the arduino send a good measure,
but my probleme is when i make a variabale resistance, in this moment the arduino sent a false measure?
can anyone help me!

(deleted)

i wante to measure the voltage between the solar cell

arhemza:
i wante to measure the voltage between the solar cell

Well one out of three is a start but not much of one.