getting error in PSO code

Hi,

I am trying to run the hybrid GA-PSO code on matlab for optimizing my objective function but I am getting this error

Array dimensions must match for binary array op.

Error in gapso (line 169)
particle(i).Velocity = w*particle(i).Velocity + c1*rand(VarSize).*(particle(i).Best.Position-particle(i).Position) +
c2*rand(VarSize).*(GlobalBest.Position-particle(i).Position);

Please help me how to resolve this.