Implementing an Enqueue function (PASCAL) - error-handling

Question

I'm having trouble getting the queue in my program to work. Every adjustment I've tried has resulted in an 'ERangeError: Range check error'.
I know this is because the program is trying to access something that doesn't exist, but I cannot figure out how to fix it.
Here is my queue implementation...
node = record //Square on chessboard
x: integer; //Row coordinate
y: integer; //Col coordinate
d: integer; //Distance from starting position
next: ^node;// (for the queue)
end; //node
coord = ^node;//'Coordinates'
queue = record//Queue w/ Linked List
head: coord;
tail: coord;
end; //queue
procedure init(var q: queue);
begin
q.head := nil;
q.tail := nil;
end; //init
function isEmpty(const q: queue): boolean;
begin
isEmpty := (q.head = nil);
end; //isEmpty
procedure push(var q: queue; m, n, o: integer);
var C: coord;
begin
new(C);
C^.x := m;
C^.y := n;
C^.d := o;
if q.head = nil then begin
q.head := C;
q.tail := q.head;
end
else begin
q.tail^.next := C;
q.tail := C;
end;
end; //push
procedure pop(var q: queue; out m: int; out n: int; out o: int);
var C: coord;
begin
m := q.head^.x;
n := q.head^.y;
o := q.head^.d;
C := q.head;
q.head := q.head^.next;
dispose(C);
if q.head = nil then q.tail := nil;
end; //pop
...and here is the main part of the function that is interacting with it.
while not isEmpty(q) do begin
pop(q, row, col, dst);
new(crd2);
crd2^.x := row;
crd2^.y := col;
crd2^.d := dst;
if valid(B, crd2) and not visited[crd2^.x, crd2^.y] then
visited[crd2^.x, crd2^.y] := true; //Mark square as visited
if (crd2^.x = Gl^.x) and (crd2^.y = Gl^.y) then
exit(crd2^.d); //Goal Check
for i := 1 to 8 do begin
crd2^.x := crd2^.x + mvmtX[i];
crd2^.y := crd2^.y + mvmtY[i];
if valid(B, crd2) and not visited[crd2^.x, crd2^.y] then begin
crd2^.d := crd2^.d + 1;
push(q, crd2^.x, crd2^.y, crd2^.d);
end;//if valid(B, crd)...
end;//for i
end;//while not isEmpty(q)
exit(crd^.d);
end;
I thought I had covered the issue by adding enough new(node) calls in the program, but the error still persists. I'm really at a loss and would appreciate any clarity you could offer.
I would email my professor but he is skiing right now and is hard to reach.
Thank you for any advice :)