hi ,
Please check that whether you have assigned the Bank format to bank account or not . Transaction is either OT85 or OT83.
Now I am sure that you haven't defined all extenernal transaction for this format . Please check your bank statment and your config .and please check whether you have done the config at right place( may be confused like t-code and did all config for manual)
Please paste the screen shot of bank statment and external transaction type assignemnt to posting rule .