Problem in crossover of parents

I want to cross over 2 parents at point 3.

parent1=1011

parent2=1100

child=1010

i want the child to take the first 3 bits from parent1 and the last bit from parent2. i wrote this code but it says that index exceeds number of array elements.

CrossoverIndex =randi([1 3]);

child= [parent1(1:CrossoverIndex) parent2(CrossoverIndex+1:end)];

can someone please guide me?