my professor created a survey and upload to department's web server.
the first time we upload survey, there's no problem occurred.
after modified some content of survey, we upload the second time,
but there's a error message below and failed:
"Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index"
when upload, there's no error and warning about survey file,
we to upload through FTP software, and there's no error occurred.
does anyone know the real problem is, and the solution?