ITunes Producer will not accept my Apple ID

Question

I created yet another Apple ID so I could submit my ebook created with iBooks Author to Apple.  I've used this new Apple ID at apple.itunesconnect.com, and also used it in iBooks Author to publish the book i.e., File -> Publish.  But whenever I try to login to iTunes Producer, I get a message saying "Your Apple ID or password was entered incorrectly".  As I mentioned, this same Apple ID and passord works everywhere else.
I suspect there is a bug in iTunes Producer when it parses the Apple ID.  Mine contains a plus sign and is similar to this:
I've read many other posts about people having problems logging into iTunes Producer as well.  I tried apple.com/support, and could not find anywhere to enter a support incident for iBooks Author or Producer.  Just great.
<Email Edited by Host>

Answer 1

I wrote - I feel sure the + is not allowed....   this is based on settting up various email accounts I use... I did not say it was NOT allowed by Apple ID sign ups.
IF  in  fact  you have creating an email and used it as your username.. then obvioulsy its OK.
You  wrote...."I created yet another Apple ID "     You need to resolve the ID issues with your original paid books account rather than  keep adding new accounts.
To confirm:-
1. Basic Apple sign up account to buy app. music etc,. ( iTunes account) 
2. Free Book account ( sign up for iTunes Connect  also with this ID) - needs to be different from above and even if not mandatory... its a wise option.
3. Paid book account/linked iTunesConnect account. Needs to be separate from (1) (2)  and needs Contracts and Banking - EIN and any specific  Apple requiremembts for your country.
4.  iTunesProducer, -  you need to make sure the account iD it is showing - or the one you login with -  is the one you want/need  to upload books. 
If you have   multiple accounts and used them in attempts to  login, it may have changed its last account used.  That said iTunesProducer v3 is a new layout and may not.