If They are staying away from it it may be to hot on that side.
If you can raise the heat lamp up above the tote. If they still stay away from it raise it some more. Til the chicks start to lay under it or around the perimeter of the heat circle it prosuces
Those plastic totes will hold a lot of heat! Raise the lamp; check the temperature on the bedding under it; consider buying a lamp with lower wattage. They are available at pet stores in the reptile section.
Chicks will let you know how they feel, when you watch them.
Mary