Procedure в Free passcal - вывод процедуры

Написал код, но выходит ошибка: am9.pas(71) : Неверное число параметров функции

program snejok_velikiy;
Uses crt;
Type
MatrixType = Array[1..20,1..20] of integer;
Var
A:MatrixType;
stolb,l,k,m,n:integer;
sz:real;

{-------------------------------------------------------------}
Procedure Vvod(Var D:MatrixType; n, m:integer; Ch:Char);
Var i,j:integer;
Begin
for i:=1 to n do
for j:=1 to m do
begin
Write(Ch,'[',i,',',j,']=');
ReadLn(D[i,j])
end
End; {Proc Vvod end}
{-------------------------------------------------------------}
Procedure Umn(Var D:MatrixType; n, m:integer; Ch:Char);
Var i,j:integer;
Begin
WriteLn('BBEDiTE 3HA4EHiE CKAJl9PA k=');
for i:=1 to n do
for j:=1 to m do
begin
D[i,j]:=D[k*i,k*j];
Read(D[i,j]);
end
End; {Proc Umn end}
{-------------------------------------------------------------}
Procedure Vyvod(Var D:MatrixType; n, m:integer);
Var i,j:integer;
Begin
for i:=1 to n do
for j:=1 to m do
begin
Write(D[i,j],' ');
WriteLn
end
End; {Proc Vyvod end}
{-------------------------------------------------------------}
Function sred(Var D:MatrixType; n, m:integer):real;
Var i:integer;
Begin
WriteLn('BBEDiTE CTOJl6ELL CPEHEE3HA4EHiE KOTOPOrO GEJlAETE HAUTi stolb=');
for i:=1 to n do
l:=0;
begin
l:=l+D[i,stolb];
sz:=l/n;
sred:=sz
end
End;
{>>>>>>>>>>BEGIN>>>>>>>>>BEGIN>>>>>>>BEGIN>>>>>>>>BEGIN>>>>>>}
BEGIN
ClrScr;
WriteLn('Laboratorna rabota 9');
WriteLn('studenta grupu KHit 12-1');
WriteLn('Pimenov Alexey');
WriteLn;
WriteLn('BBEDiTE KOJl-BO CTPOK MATRiXy n=');
ReadLn(n);
Write('BBEDiTE KOJl-BO CTOJl6lLOB MatriXy m=');
ReadLn(m);
{Proc}Vvod(A, n, m, 'A');
ClrScr;
{Proc}Umn(A, n, m, 'A');
WriteLn('CPEDHiE 3HA4EHie BBEDEHOro BAMi CTOJl6lLA A=', sred(A[n,m]));
End.

Помогите решить проблему