i believe there may be a problem with entering my switch case

i am using this code to read a value from the moisture sensor and light up an led depending on the moisuture. however when i run this code it makes it as far as reading the moisture value and not doing anything else. any help at all would be greatly appreciated

code for reference:

clear

clc

a = arduino();

PB = 'D8';

key = readDigitalPin(a,PB);

pbc = 0;

b = mod(pbc, 3);

moisture = readVoltage(a,"A0")

while true

switch b

case 0

if moisture >= 4 && moisture <= 5

writeDigitalPin(a,'D2',1) % green

writeDigitalPin(a,'D4',0) % orange

writeDigitalPin(a,'D7',0) % red

%writePWMVoltage(a, 'D11',1.67)

pause(5)

writePWMVoltage(a, 'D11',0 )

pause(120)

else

writeDigitalPin(a,'D2',1) % green

end

case 1

if moisture >= 3 && moisture <= 4

writeDigitalPin(a,'D2',1) % green

writeDigitalPin(a,'D4',0) % orange

writeDigitalPin(a,'D7',0) % red

%writePWMVoltage(a, 'D11',1.67)

pause(5)

writePWMVoltage(a, 'D11',0 )

pause(120)

else

writeDigitalPin(a,'D2',1) % green

end

case 2

if moisture >= 2 && moisture <= 3

writeDigitalPin(a,'D2',1) % green

writeDigitalPin(a,'D4',0) % orange

writeDigitalPin(a,'D7',0) % red

% writePWMVoltage(a, 'D11',1.67)

pause(5)

writePWMVoltage(a, 'D11',0 )

pause(120)

else

writeDigitalPin(a,'D2',1) % green

end

end

if key == 1

pbc = pbc + 1;

end

end

Answer 1

[Alexander]

Shouldn't be

moisture = readVoltage(a,"A0")

not also in the while-loop?