VERY tough to know if an eel is eating... I remember William's posting and I remember numerous others on the same subject. Some ended happily; some did not.
As most eels are nocturnal, it's impossible to tell whether how much they're eating, and, indeed, if they are at all. I agree emphatically with William's ghost shrimp idea. Live food avoids the problem of food rotting in the tank and going uneaten. Try to get the smaller shrimp. I'm alsmost certain you'll have no shrimp left in a few days.
*However* be very careful with shrimp. They, as much as any fish, can carry diseases into your tank. I'd advise quarantining the inverts in another tank for 2 weeks before feeding. This requires thinking ahead and stocking!!
Hope this helps!