terminate called after throwing an instance of 'std::runtime_error'

[gongqingfeng]

When I run "./fesvr-zynq pk hello" on my zybo, I get a right result "hello!". However, I get some errors like this:
terminate called after throwing an instance of 'std::runtime_error'
what(): could not open bbl

when I run "./fesvr-zynq bbl" on my zybo.
Has anyone met the same errors?
Thank you.