How to change linetype in ggplot if scale_linetype_manual doesn't work?

Question

I'm trying to set linetypes of variables, but scale_linetype_manual is having no effect to the final plot.

I tried many solutions such as defining

scale_linetype_manual(name="Legend", values=c(1,2,1,2,1,2,1,2))

and defining my linetype directly in my dataframe.

Here is my dataframe appearence

X Y type
1 9 1A
1 7 1A
3 8 1A
4 7 2A
2 6 2A
1 7 2A
4 6 1B
5 7 1B
6 6 1B

So I made my ggplot like this:

legend.title = "Domains"
ggplot(df) +
  geom_line(aes(x=X, y=Y, color=type)) + 
  xlim(0,50) +
  scale_color_discrete(legend.title) +
  scale_linetype_manual(name=legend.title, values=c(1,2,1,2,1,2,1,2,1,2))

Here is my result:

I'm only getting type 1 lines.

Do you have any idea? Thanks.