Plotting graphs with best fit lines

Hello, I'm attempting to plot a "Pressure Change as a function of Voltage" with given data points. The plot should have the points, a best fit line and two lines of uncertainty on either side of the 'best fit line'. Currently my uncertainty lines are FAR below. Request assistance.

(My understanding of my jacked up legend is that there is something with my current driver and my 2020b Matlab, I'm not too worrried about that)

V=[1.000 2.000 2.500 3.000 3.500 4.000]'; %Voltage (V) with 0.05 accuracy
P=[626 948 1452 1727 1798 2001]'; %Pressure drop (Pa) +/-20 

eV=0.05*ones(size(V));
eP=20*ones(size(P));
wVal=1./(eP/mean(eP));

errorbar(V, P, eP, eP, eV, eV, 'kx');
[fobj, gof]=fit(V,P,'poly1', 'Weights', wVal);
hold on
plot(fobj)
plot(range, PInt, 'b')

legend('data', 'cal curve', 'PI', 'Location', 'Northwest', 'Linewidth', 1)

title('Pressure Drop as funciton of Voltage')
xlabel('Voltage (V)')
ylabel('Pressure Change (Pa)')
axis square
box on
set(gcf, 'Color', 'w')

[Patrick Struszczyk]

[dpb]

plot(range, PInt, 'b')

range and PInt are undefined above. Clearly, they must have been from some other dataset than that in V,P

[Patrick Struszczyk]

Thank you!