PROBLEM:

In version 1.8.0 and 1.8.1, file upload fields are not showing up, even when all configuration parameters are entered correctly.

DISCUSSION:

When transitioning from version 1.7.x to version 1.8.x, a feature was added which allows you to specify multiple file upload fields.  Unfortunately, the default value is "Y" and you only have the options to set "Y" to "N" which results in the number of fields being set to "Y" which gets interpreted as 0 fields.

SOLUTION:

Upgrade to version 1.8.2 or later.