device not supporting the .pka and other extensions in 7.1.1

[saurabhsubba]

Hi everyone there,

I am beginner here, i downloaded cisco packet tracer version 7.1.1 (student version); initially it worked couple of time and when i tried to download .pka OR .pkt it say like this as shared in this screen shot picture.r

thank you in advance for yours help and idea.

with regards

Saurabh Subba