[NTG-context] Custom background color for \framed inside lmt_text

I want my custom color rose_color to be applied for background color for \framed inside lmt_text. For fill fullcircle, it works. With predefined colors as green, it works. \starttext \startMPcode color rose_color; rose_color = 1/256(255,204,255); %not working draw lmt_text [text ="\framed[background=color,backgroundcolor=rose_color,frame=on, location=low]{a rose box}",]; %working draw lmt_text [text ="\framed[background=color,backgroundcolor=green,frame=on, location=low]{a green box}",] shifted (1cm,1cm); %working fill fullcircle scaled 2cm shifted (0,3cm) withcolor rose_color; \stopMPcode \stoptext