I'm not seeing any problem. I'm using PelicanHPC 64 bit, a development version which is essentially the same as the last released version. See the attached screenshot. If you specify the full path to mpif77, do you see the problem? What version of PelicanHPC are you using (not that it should matter)?
My suspicion is path troubles, for some reason. Are you compiling as root by any chances?
mpif77.png