Function not working if more then 1 Record is selected

Function not working if more then 1 Record is selected

Hi there!

I have a function like this:

string button.PCS_TempDruck_Rechnungen(string Modul, int ID)
{
//Do some stuff here
return "finish"
}

I linked this function to a button in the List View and Mass/Multi-Action of the Quote Module.
Arguments:
Module = "some fix String"
ID = Quote.id

If I select only one record in the List and press the button, everything works fine. But if i select 2 or more records, I get the error message "Value given for the variable 'ID' does not match its type at Line Number: 1".

I also checked if the IDs are sent as list, map or something like this, but I think that's not the case. When I change the type of ID from Integer to String, I get the Numbers, but can not change it later toInteger() or toLong(), because Deluge don't believe me that it is  a number and insists it is text ;-) And since I want to get some Data in the function like customDetails = zoho.crm.getRecordById(Modul,ID) it has to be a integer.

What am I missing?

Thank you in advance for your help.

Greetings: Stefan