404 error when uploading pictures

On one of my cms builder admins I have an upload field.  Every time I try to upload something I get a 404 error.  I can upload images through the wysiwyg editor but not the upload.  I can log in to another cms builder on the same server and upload the pics just fine.  I was able to upload when i first installed the script. I'm running version 2.61, can some one help?