ask for help on open() function

shiyiming

data a;
x=1;
data b;
y=2;
run;

%let dsida=%sysfunc(open(a));
%let dsidb=%sysfunc(open(b));
%let dsida=%sysfunc(open(&dsida.));
%let dsidb=%sysfunc(open(&dsidb.));

I tried the cod above(just try to open datasets a and b, and then close them), looks good, but datasets a and b are open, and I can not close them even I used close() function. and re-run it, give me errors. both a and b are not be closed.
anything is wrong with my code, somebody could help me? Thanks a lot.

shiyiming

Your description is not clear. Please clarify your question, so somebody can help you. cheers