Changing the scale of x-axis using scale_x_continu

Question

I am creating a scatter plot using ggplot2. The default gives me an x axis that has every value form 0 to 30. I'd prefer to have it go by 5s or something like that. I have been trying to use scale_x_continuous(), but I get this:
Error: Discrete value supplied to continuous scale

Here is the code that I am trying to work with:

Daily.Average.plot <- ggplot(data = Daily.average, aes(factor(Day), Mass))+
  geom_point(aes(color = factor(Temp))) + 
  scale_x_continuous(breaks = seq(0,30,5))

Daily.Average.plot

When I run this without the scale_x_continuous I get a graph that looks fine with no errors, just the incorrect x axis. All of the columns in the data set are numeric when I check str(), if that matters. Do I have an error in my code, or should I be using something different to change the scale?

Here is a sample of my data set:

N   Day       Mass Temp
1    1 0.00000000    5
2    2 0.00000000    5
3    3 0.07692308    5
4    4 0.07692308    5
5    5 0.07692308    5
6    6 0.15384615    5
7    7 0.15384615    5
8    8 0.23076923    5
9    9 0.38461538    5
10  10 0.46153846    5
11   1 0.00000000   10
12   2 0.00000000   10
13   3 0.00000000   10
14   4 0.09090909   10
15   5 0.09090909   10
16   6 0.54545455   10
17   7 0.54545455   10
18   8 0.63636364   10
19   9 0.90909091   10
20  10 1.36363636   10
21   1 0.00000000   15
22   2 0.07692308   15
23   3 0.61538462   15
24   4 0.76923077   15
25   5 0.76923077   15
26   6 1.23076923   15
27   7 1.69230769   15
28   8 2.07692308   15
29   9 2.46153846   15
30  10 3.07692308   15