Not enough input arguments in Matllab Code

function X=initialization(nP,dim,ub,lb)

Boundary_no= size(ub,2); % numnber of boundaries

% If the boundaries of all variables are equal and user enter a single
% number for both ub and lb
if Boundary_no==1
X=rand(nP,dim).*(ub-lb)+lb;
end

% If each variable has a different lb and ub
if Boundary_no>1
for i=1:dim
    ub_i=ub(i);
    lb_i=lb(i);
    X(:,i)=rand(nP,1).*(ub_i-lb_i)+lb_i;
end
end

while running this code I'm getting this

Not enough input arguments.

Error in initialization (line 43) Boundary_no= size(ub,2); % numnber of boundariescode here

can someone help me with this error thank so much