Cannot query field \"namespaceList\" on type \"Query\"."

Find below example , the query "namespaceList" is not picking, it shows "Cannot query field \"namespaceList\" on type \"Query\"." error .
var Query = graphql.NewObject(
graphql.ObjectConfig{
Name: "Query",
Fields: graphql.Fields{
"namespaceList": &graphql.Field{
Type: kubernetes_schema.ListNameSpaceResponse,
Description: "kubernetes cluster namespace list",
Args: graphql.FieldConfigArgument{
"clusterId": &graphql.ArgumentConfig{
Type: graphql.NewNonNull(graphql.String),
},
},
Resolve: kubernetes.ListNameSpace,
},