Creating and using AzureChatOpenAI directly works fine, but crashing through ChatVectorDBChain with "ValueError: Should always be something for OpenAI."
This is fixed in [v0.0.117](https://github.com/hwchase17/langchain/releases/tag/v0.0.117) Argh apologies, I updated it to that version but in wrong conda environment.
Sorry about that. Thanks a lot.
Creating and using AzureChatOpenAI directly works fine, but crashing through ChatVectorDBChain with "ValueError: Should always be something for OpenAI."

Example:
```
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.vectorstores import FAISS
from langchain.text_splitter import CharacterTextSplitter
from langchain.chains import ChatVectorDBChain
from langchain.document_loaders import  PagedPDFSplitter

from langchain.chat_models import AzureChatOpenAI
from langchain.prompts.chat import ChatPromptTemplate, SystemMessagePromptTemplate, AIMessagePromptTemplate, HumanMessagePromptTemplate
from langchain.schema import AIMessage, HumanMessage, SystemMessage

system_template="""Use the following pieces of context to answer the users question. 
If you don't know the answer, just say that you don't know, don't try to make up an answer.
----------------
{context}"""

messages = [
    SystemMessagePromptTemplate.from_template(system_template),
    HumanMessagePromptTemplate.from_template("{question}")
]
prompt = ChatPromptTemplate.from_messages(messages)

loader = PagedPDFSplitter("myfile.pdf")
text_splitter = CharacterTextSplitter(chunk_size=700, chunk_overlap=50)
documents = loader.load_and_split(text_splitter)
embeddings = OpenAIEmbeddings(chunk_size=1)
vectorstore = FAISS.from_documents(documents, embeddings)

qa = ChatVectorDBChain.from_llm(AzureChatOpenAI(temperature=0, deployment_name='gpt-35-turbo'), vectorstore, qa_prompt=prompt, top_k_docs_for_context=2)

## All good to here, but following line crashes:

result = qa({"question": "what is section 2 about?", "chat_history": []})
```

Crashes with:
             ValueError: Should always be something for OpenAI.

This works fine on ChatOpenAI but not AzureChatOpenAI.