New Post: GetUserTimelineAsync throws exception

I did notice that the calls that fail don't have the key and token in the header:

Works:
GET : https://api.twitter.com/1.1/users/show.json?screen_name=@AAAAAAA
Header OAuth oauth_consumer_key="XXXXXXXXXXXXXXXX",oauth_nonce="11111111",oauth_signature_method="HMAC-SHA1",oauth_timestamp="11111111111",oauth_token="xxxxxxxxxxxxxxxxxxxxxxxx",oauth_version="1.0",oauth_signature="XXXXXXXXXXXXXXXXXX"

Works:
GET : https://api.twitter.com/1.1/statuses/user_timeline.json?user_id=11111111&include_rts=True&exclude_replies=False&contributor_details=False&count=10&trim_user=False&include_entities=True
Header OAuth oauth_consumer_key="XXXXXXXXXXXXXX",oauth_nonce="111111111",oauth_signature_method="HMAC-SHA1",oauth_timestamp="111111111",oauth_token="xxxxxxxxxxxxxxxxxxxxxx",oauth_version="1.0",oauth_signature="XXXXXXXXXXXXXXXX"

Fails:
GET : https://api.twitter.com/1.1/users/show.json?screen_name=@BBBBBBB
Header OAuth oauth_nonce="1111111",oauth_signature_method="HMAC-SHA1",oauth_timestamp="111111111",oauth_version="1.0",oauth_signature="XXXXXXXXXXXX"