problem with join command

[kevin]

I want to use join command with this 2 files :
test1:
1 a
2 a
3 a
45 a
78 a
152 a
1896 a

test2:
1 a
2 a
3 a
152 a
1896 a

When i do : join test1 test2
the result is :
1 a
2 a
3 a

and not :
1 a
2 a
3 a
152 a
1896 a

Thanks for your help

Kevin