Not getting the PUT verb in django-rest-framewrok

gistfile1.py

# serializers.py

from .models import FGItem, FGTaken
from rest_framework import serializers


class FGItemSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = FGItem
        fields = ('code', 'description', 'uom',
                  'factor', 'upc', 'upc_pack', 'cost')


class FGTakenSerializer(serializers.HyperlinkedModelSerializer):
    warehouse = serializers.SlugRelatedField(slug_field='warehouse_id')
    code = serializers.SlugRelatedField(slug_field='code')

    class Meta:
        model = FGTaken
        fields = ('slip', 'warehouse', 'code',
                  'qty1', 'part1', 'qty2', 'part2')


# views.py

class FGItemViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows FGItem to be viewed or edited.
    """
    queryset = FGItem.objects.all()
    serializer_class = FGItemSerializer


class FGTakenViewSet(viewsets.ModelViewSet):
    """
    API endpoint that allows FGTaken to be viewed or edited.
    """
    queryset = FGTaken.objects.all()
    serializer_class = FGTakenSerializer

# urls.py
from rest_framework import routers

router.register(r'fgitem', FGItemViewSet)
router.register(r'fgtaken', FGTakenViewSet)

...
url(r'^api/', include(router.urls)),