[newbie] how to change plot legend



I'm trying to replace the automatically generated legend in the following 
codefragment:
deltaurlrel(x):=1-1/(x*(1-x)*%beta+1);
relplots:makelist(deltaurlrel(x),%beta,[0.1,0.213,0.444,1,4.545]);
plot2d(relplots,[x,0.01,1],[gnuplot_preamble,"set grid",legend,"%beta=0.1","%beta=0.213","%beta=0.444","%beta=1","%beta=4.545"])$

unfortunately the plot keeps showing the automatically generated legend

any help appreciated

hugo