API:Get_Transactions details

Hello,
when using the API:Get_Transactions to get the details of a transaction, the system is looking for the Trans ID field, which is not unique.

I want to be able to get the details according to the unique ID field from the tbl_transactions (which is perfectly exported on the reports).

is that possible?

MtK

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btw, why is $admin a required field?
what is it used for, and why is the API still usable without it...?