Galvanic cell with Zn and Fe(NO3)3 measured 0.287V instead of expected 1.53V

[supercali]

iwe had an expirament that goes like this
we made a galvanic cell with half cell zinc and its solution (Zn(NO3)2) and the other half cell was with iron and its solution (Fe(NO3)3) (the Fe solution with ions Fe+3) (both same concentration!) the potential i measured was 0.287V
now i just don't understand how can this be
because the standard potential of Fe+3 + e -> Fe+2 is 0.77V and for Zink it is -0.76V thus we should get in the experiment that the measured potential is 1.53V i just can't understand my result
help please

 

[Borek]

You won't get different answer here than the one I have posted on chemical forums.