You have specified an identifier which does not represent a procedure or function in an EXPORTS clause.

library Produce;

  var
   y : procedure;

exports y;
begin
end.

It is not possible to export variables from a built-in library, even though the variable is of 'procedure' type.

program Solve;

  procedure ExportMe;
  begin
  end;

exports ExportMe;
begin
end.

Always be sure that all the identifiers listed in an EXPORTS clause truly represent procedures.