Why can't i get my tamgotchis to connect?

i have two, they are different generations but i know theey can still connect. i am notcactly sure what generations are, though. one is yellow,red and different shades of orange and is decorated with what looks like binary code. it has a red ball on the antenna and it is and english version.the other i am pretty sure is version 4.5, it has an earth pattern and has a star shape on the antenna. it is also an english version.Help? please and thanks!