IP Overlaping

[EWoodie]

So Im a student using Cisco Packet Tracer, Im trying to make a network, but while configuring my edge routers I keep running into an issue of it "overlapping" with another port, Im not sure whats going on as Im just following what they said, so, Im now lost as they wont give me a straight answer of what im doing wrong

My GE1/0 is configured as 

10.0.1.1/24

My GE2/0 Ive tried to configure as GE 10.0.4.1/24 but its comes up with "10.0.4.1 255.0.0.0 overlaps with GE1/0" 
If I change it wo 11.0.4.1 it works, but the spec sheet asks for it to be 10.0.4.1. 
Im lost on where ive made the mistake, or if I even have made a mistake.

[MHM Cisco World]

10.0.4.1 255.0.0.0 <<- must be 255.255.255.0

[Martin L]

10.0.4.1/24 falls into range of  10.0.4.1 /8 since /8 makes only 1st 8 bits matter for network id and rest are for  hosts;

range for 10.0.4.1 /8 is 10.0.4.1 -10.255.255.254 (b-cast is 10.255.255.255), so you can see any 10. x.x.x /24 is overapping.

Regards, ML
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