C# Collision Detection Problem

protected void CollisionHandle(List<List<WorldTile>> TileMap)
        {
            int leftTile = (int)Math.Floor((float)_Collbox.Left / WorldTile.Width);
            int rightTile = (int)Math.Ceiling(((float)_Collbox.Right / WorldTile.Width)) - 1;
            int topTile = (int)Math.Floor((float)_Collbox.Top / WorldTile.Height);
            int bottomTile = (int)Math.Ceiling(((float)_Collbox.Bottom / WorldTile.Height)) - 1;

            _OnGround = false;

            for (int y = topTile; y <= bottomTile; y++)
            {
                for (int x = leftTile; x <= rightTile; x++)
                {
                    TileCollision collision = TileCollision.Empty;
                    if (y >= 0)
                    {
                        if (x >= 0)
                        {
                            if (y < TileMap.Count && x < TileMap[y].Count)
                                collision = TileMap[y][x].Collision;
                        }
                    }

                    if (collision != TileCollision.Empty)
                    {
                        _TileBounds = new Rectangle(x * WorldTile.Width, y * WorldTile.Height, WorldTile.Width, WorldTile.Height);
                        Vector2 depth = IntersectDepth(_Collbox, _TileBounds);
                        if (depth != Vector2.Zero)
                        {

                            float absDepthX = Math.Abs(depth.X);
                            float absDepthY = Math.Abs(depth.Y);

                            if (absDepthY <= absDepthX || collision == TileCollision.OneWay)
                            {
                                if (_PreviousBottom <= _TileBounds.Top)
                                    _OnGround = true;

                                if ((collision == TileCollision.Solid) || _OnGround)
                                {
                                    Position = new Vector2((int)Math.Round(Position.X), (int)Math.Round(Position.Y + depth.Y));
                                    UpdateCollBox();
                                }
                            }
                            else if (collision == TileCollision.Solid)
                            {
                                Position = new Vector2((int)Math.Round(Position.X + depth.X), (int)Math.Round(Position.Y));
                                _FacingRight = !_FacingRight;
                                _Velocity.Y = 0;
                                UpdateCollBox();
                            }
                        }
                    }
                }
            }

            _PreviousBottom = _Collbox.Bottom;
        }

        private void UpdateCollBox()
        {
            _Collbox = new Rectangle((int)Math.Round(Position.X), (int)Math.Round(Position.Y), Animation.FrameWidth, Animation.FrameHeight);
        }

        private Vector2 IntersectDepth(Rectangle rectangleA, Rectangle rectangleB)
        {
            float halfWidthA = rectangleA.Width / 2.0f;
            float halfHeightA = rectangleA.Height / 2.0f;
            float halfWidthB = rectangleB.Width / 2.0f;
            float halfHeightB = rectangleB.Height / 2.0f;

            Vector2 centerA = new Vector2(rectangleA.Left + halfWidthA, rectangleA.Top + halfHeightA);
            Vector2 centerB = new Vector2(rectangleB.Left + halfWidthB, rectangleB.Top + halfHeightB);

            float distanceX = centerA.X - centerB.X;
            float distanceY = centerA.Y - centerB.Y;
            float minDistanceX = halfWidthA + halfWidthB;
            float minDistanceY = halfHeightA + halfHeightB;

            // If no intersection is happening, return Vector2.Zero
            if (Math.Abs(distanceX) >= minDistanceX || Math.Abs(distanceY) >= minDistanceY)
                return Vector2.Zero;

            // Calculate instersection depth
            float depthX = distanceX > 0 ? minDistanceX - distanceX : -minDistanceX - distanceX;
            float depthY = distanceY > 0 ? minDistanceY - distanceY : -minDistanceY - distanceY;
            return new Vector2(depthX, depthY);
        }