Error in CVX using SDP constraints

HI! following is the code i have writted for coordinated beamforming using instantaneous channel state information. The code is giving me an error in the matrix constratints ,possibly concatenation.
I would really appreciate if you guys can identify the error as I am stuck and cannot debug my code,

Thank you in advance

clc;
close all;
clear all;
N=3;%number of cells
K=1;%number of user in each cell
U=3;%total number of users
M=6;%number of antenna per cell

W=zeros((N*M),K);
H=zeros(N,(N*M));

I=eye(N,N);
O=zeros(N,N);
P=zeros(N,(N*K));
L=zeros(1,K);
gamma=10;
a=sqrt(1+(1/gamma));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

for i=1:K;
w_i=randn((N*M),1); 
disp('&&&&&&&&&&&&&&&')
disp (w_i);
W(:,i)=W(:,i)+w_i;

end;
disp(W);
%filter specifications
for i=1:K;
for q=1:N
h_q= randn(1,M);
disp(h_q);

 if q>1

 H=blkdiag(H,h_q);
 
 else

        H=h_q;
        
 end;

   
end;
disp(H);
 if i==1
     Hp=H;
 elseif i>1
     Hp=vertcat(Hp,H);
 end;
 L(i)=N;

end;

disp(Hp);
C=mat2cell(P,N,[L]);
for i=1:K
 C{1,i}=I;

P=cell2mat(C);
disp(P);
C{1,i}=O;
e_i=zeros((N*M),1);
e_i(i)=1;
disp(e_i);
end;
for p=1:N
e_p=zeros(N,1);
e_p(p)=1;
disp(e_p);
end;

%%%%%%%%%%%%%%%%%%%problemmm%%%%%%%%%%%%%%%%%%%%

cvx_begin sdp
cvx_solver sedumi
variable x
variable W
l=[(vec(P*Hp*W))'    10];
m=[ vec(P*Hp*W) ; 10];

minimize(x)

Y =[ a*(e_p)'*P*(Hp)*W*e_i         l ;......
    m  (a*(e_p)'*P*(Hp)*W*e_i)*I]>=0;

D=[ x   (vec(W))'...
   vec(W) x*I] >=0;


 1<=p<=N;
 1<=i<=K;
 cvx_end;
 
 disp(x);

If you’re going to use all caps in the title, the least you could do is provide us with a copy of the error message itself.