The resistors in your LM317 voltage regulator are far too high. The resistor from the OUT pin to the ADJ pin should be 120 ohms and for the regulation to be 7.1V then the resistor to ground should be 560 ohms.
During charging, the current regulator regulates the current. When the battery is fully charged at about 5.6V then the input of the current regulator will be about 7.1V.
You have R1 completely destroying the current regulation so remove it.
Why is your input voltage (18V) much too high?
Where is the battery?
I don't think Multisim knows anything about an LM317 and neither do you.