Post account not eligible for paycheck?

Today I received an e-mail from my current part-time job saying that my JP Post account is not eligible to receive my paycheck.

I made my account in September 2012 so it is well past the 6 month limitation on bank transfers. I have received other paychecks from previous part-time jobs (two other jobs) with no problem whatsoever. My rent is withdrawn from my account each month with no problems either.

My boss says he can't pay me until I fix it and seems to think the problem is entirely on my end...I can speak some Japanese but banking terms go over my head. Any ideas about what the issue might be?

It's a small company, so I thought maybe he's trying to transfer money from a personal account instead of a business account...but other than that, I've no idea...

your account is still 通常貯金.
you have to take some paperwork to change your account to 総合口座. (the changing is not automatic.)
if your employer sends money as 給与 to your account,通常貯金, it may be received. but your 通常貯金 can't receive regular wire-transfers (from person A to person B).
go to the nearest post bank office with your bank book and ID, and ask them change your account from 通常貯金 to 総合口座.

Yu-cho bank uses it original branch code which only valid in Yu-cho transaction system. However you need to convert the branch code while payees send money into your Yu-cho bank a/c.

If your Yu-cho bank a/c number starts from "1", eg;11940-12345671, the 2nd and 3rd digit number "1" and "9" + "8", "198" is your Yu-cho branch number, and remove the last digit number of your Yu-cho bank a/c, in this case "1", "1234567" is the translated number.
Therefore, "198-1234567" is the valid bank a/c other than Yu-cho system.

If your Yu-cho bank a/c number starts from "0", eg, 01930-1-123456, the 2nd and 3rd digit number "1" and "9" + "9", "199", ignore the middle number of "1", and then bank number of "123456".
Therefore, "199-123456 " is the bank a/c number you need to tell to your employer.

or use this convert site.
https://wwws.jp-bank.japanpost.jp/cgi-bin/kouza.cgi

Yu-cho bank code is "9900" which doesn't normally require to send money transfer in JP.