When I try to add two columns together SAS generates a missing value on the first record. Why?

[mreynaud]

Hello SAS community!

When I try to add two columns together SAS generates a missing value on the first record.

Here is the sample code I'm running using the SAS Help library:

data test;
sum=sum(vsp,pop);
keep sum vsp pop;
set sashelp.tourism;
run;

I am attempting to calculate a sum between two columns, I keep on getting a missing value for the first record of the sum column and the it shift the corresponding sum one record down. See below:

What I want is the sum between two columns all on each respective row: 

sum	vsp	pop
55.9253	1.2823	54.643
56.2308	1.2718	54.959
56.753	1.537	55.216
57.4111	1.9501	55.461
57.462	1.83	55.632
58.5406	2.6126	55.928
59.2325	3.1535	56.079
59.2831	3.0601	56.223
58.8326	2.5966	56.236
59.1075	2.8815	56.226
58.3674	2.1514	56.216
58.734	2.544	56.19

and so on...

Please help! I've tried using coalesce with the sum but all it did was is convert the missing value into a zero.

Thank you in advance

[PaigeMiller]

Move the SET statement to above the SUM

[Tom · Accepted solution]

It is very hard for SAS to add values together BEFORE it actually HAS the values!

Fix the order of your statements so they make sense.

data test;
  set sashelp.tourism;
  sum=sum(vsp,pop);
  keep sum vsp pop;
run;