Custom domian reg module problem with next due date

[cosmin]

Hi!
We made a custom module for tld domains registration and we have a problem.
All .tld domains has nothing at field "Expiry Date",  we imported and populated the field "Next Due Date" after a query to get expiry date. After every renewal WHMCS remove everything from "Next Due Date" and add the date today+nr of years renewals at "Expiry Date" 

What we need to do for "Next Due Date" update with new expiry date and ignore "Expiry Date" (or put the same data from "Next Due Date"?

We tried something simple like

$values['nextduedate'] = $expdate;
$values['nextinvoicedate'] = $expdate;

but nothing, I think value nextduedate is named different.

Thank you very much!

[nasos75]

You have to implement _Sync functions in your module. Then according to Setup/Domains/Sync Next Due Date, your dates will be updated.