auto increment not working

auto increment not working

I have an application with a master form and two linked sub-forms, one of which is for support tickets. I would like to have Zoho automatically assign a unique ID number for each ticket when it is entered. 

I tried following the instructions here:  http://kbase.creator.zoho.com/application/auto-increment-field-values. However, there are two issues:

1. This only works when adding the ticket directly in the sub-form, but not when adding it in the master form. However, users will only ever enter support tickets through the master form.

2. The incrementer just adds a 1 to the end of whatever the max value is, rather than increasing the value by 1 (e.g., if the max value in the max value holder form is 12, it assigns a support ticket number of 121, not 13 as it should have).

Any help would be greatly appreciated!