Operating system error code 3(The system cannot find the path specified.)

Question

I have two servers. One is a web server and one is a sql server. What I'm trying to do is as follows:

  User uploads a document to a web server.
File is stored on a web server in a directory, verified that it's a
certain type of file, and saved.
When the user presses a submit button, the page is uploaded and the Onclick event triggers a sql bulk insert (not on the same web server.)

That's it in a nutshell. The basics of this page are done. The file can be saved but for whatever reason, I'm getting a Operating system error code 3(The system cannot find the path specified.)

I've modified the machine.config on the web server to impersonate another user. I've made sure that the directory in question can be reached from both servers (and it can.) I can open/edit/delete the file  from the directory from both sides, but evidently that's not the issue.
I can post my code here if necessary.
thank you

Doug