[NTG-context] m-graph label

The horizontal axis label of mwe below has 0.0 (showing tenths; pdf attached; filename is mwe.tex). I expected it to show -1, 0, 1, 2, 3, (integers only). Can this be formatted? % -1 1 % 0 1 % 0 2 % 1 1 % 2 1 % 2 2 % 2 3 % 2 4 % 3 1 % 3 2 \usemodule[m-graph] \startMPpage[instance=graph, offset=5mm] labeloffset:=3mm; draw begingraph(8cm,4cm); setrange(-1.5,0.5,3.5,5); picture symbol ; symbol := image(draw fullcircle scaled 5mm withcolor red;); gdata("mwe.tex", v, clearxy; glabel(symbol,v1,v2) ; ); frame.bot shifted(0,-2mm) ; autogrid(otick.bot,) shifted(0,-2mm); endgraph; \stopMPpage Thanks! John