UDT - Copying rows from Excel

Dear Experts,

As you know, in SAP Business One 9.1 you can copy and paste datas from excel.

I created a UDT and I want to copy rows from excel.

When I paste the rows, I get this error : "The target table cannot add new rows automatically. Contents below row '1' were not copied."

How can I change the table type to add new rows automatically?

Thanks in advance,

Regards,

Onur