Aorist of προδίδωμι?

[Shwump]

I am currently working on the Greek to English exercises in Chapter 14 of A New Introduction to Greek by Chase & Phillips. I seem to be having a problem though, with one of the sentences, (number 5, if you happen to have the book) which reads, "the ancients never betrayed each other." It seems to me that the aorist of προδίδωμι should be πρέδωκα. However, I am unable to find this form on the Perseus resource. If anyone can shed some light on this, I would appreciate it greatly!

[NateD26]

προ- does not lose its vowel before augments, but contracts to προὔδωκα.
Here it should be προὔδωκαν. [edited.]

[Shwump]

Ah, I see that I need to review that. Thank you very much!