reg Measure tool

Dear All,
i am a new user, I was trying ti get familiar with DS viewer etc.
all went on fine

for some reasons .. whenever i try to measure the bond distance between 2 atoms in aromatic ring, instead of giving the distance it gives me zero , i think it measures the angle.
for any 2 atoms it measures only the angle between the respective planes

is it some sort of bug ..

can anyone help me out

thanks in advance
Sincerely,
Karthick