how to include a do loop inside a macro in SAS?

Following is an example of the data-set I have

data have;
input institution$ GPA;
cards;
    A   3.2
    AB  3.4
    BC  4.0
    DF  3.2
    A   4.0
    A   3.0
    A   3.5
    A   3.7
    A   3.8
    F   3.8
    D   3.2
    D   3.1
    D   3.7
;
run;

Essentially I want to create a macro that selects a random sample from this data set (the actual dataset is much larger). I also want to simulate this sampling procedure, so that for e.g I can do 50 sampling iterations and for each iteration, I get a output data set. I tried creating the following macro to do this

%macro beta (maxj=,datain= ,numofsamples= , dataout=,);
%do j=1 %to &maxj;
proc surveyselect data=&datain
   method=srs n=&numofsamples out=&dataout_&maxj;
run;
%end;
%mend;


%beta (maxj=4 ,datain=have ,numofsamples=5,dataout=pool);

Essentially when I run this, want to get outputs data sets so that they are named pool_1,pool_2,pool_3 etc.

However, when I run this macro it doesn't seem to do what I intended. Instead it shows that there is something wrong with the &dataout_&maxj; run;line