Rich,
This type of error appears when settings are incorrect. Recommended steps:
Get from your webhost the following:
Read the respective help file on how to use the information above to create a correct Upload Preset in Step 6 of Shozam
If you are still have issues, contact Helpdesk with the following:
You an also upload using any other third party FTP application, like FileZilla or any other one which Yahoo webhosting may recommend.