Cause:**One of the following:
1. You entered a nonexistent form name.
2. You typed an incomplete path.
3. You do not have the proper privileges to run the form.
4. You do not have a compiled copy of the form.
Action:**Retype the form name correctly, provide the proper path name, compile the form, or contact the DBA.
If your operating system is MS WIndows (XP?), then open registry editor and navigate to HKEY_LOCAL_MACHINE/ORACLE/HOME0. Locate FORMS90_PATH string and modify its value - add a directory which contains your forms (separate it from the rest of the string with a semi-colon).
DEFAULT.ENV is a file located in ORACLE_HOME\FORMS90\SERVER directory. Open it with any text editor and set FORMS90_PATH to point to a directory which contains your forms.
Someone will certainly run into the situation you were in.
You came here asking for help.
Now that you solved it, it would be nice if you post the solution NOW!, not waiting until someone says "Hey, how did you do that?". You might be on 3-months vacation. You might stop working with Oracle. You might stop visiting dBforums. You might ... whatever.
So, post it now, share the knowledge. Don't keep it for yourself.