Because it's useless without the arming code. Someone arranged an accident for Professor Waddlemeyer last year before I could learn it.

10 seconds sound clip from the Darkwing Duck - Darkly Dawns the Duck: Part 1 (S01E01) movie soundboard.

You can hear this line at 00:13:53.066 in the DVD version of the TV Series.

Quote context

[...]

- Maybe you'll get some time off for good behavior... in 99 years or so.

- I sure wouldn't mind poundin' that pinhead.

- Ignore him. Such petty annoyances will disappear once I use the Ramrod.

- Oh, jeepers. It's beautiful.

- So why don't we fire it up and hit a few banks?

- Because it's useless without the arming code. Someone arranged an accident for Professor Waddlemeyer last year before I could learn it.

- Eh! You idiots! I told you not to...!

- Go to the St. Canard orphanage and bring me his granddaughter. She was practically raised in his lab.

- If anyone knows the code, she does.

- After we get the code, then she can have an accident like her grandfather.

[...]