I upgraded my yahoomail to the newest version but now i cant go into my Yahoo Small Business anymore?

Hi all, i upgraded my personal yahoo mail into the newest version but then when i press into my Yahoo Small business email account, not even 3 secs, it automatically turned back into my personal yahoo email folder...izzit some bug or trouble shoot happened for the new version of the yahoomail?? any solution for me to solved this problem as i need my Yahoo Small Business email to contact with my customer. Thank in advance.