Orvis Full Flex fiberglass fly rod and carp

I caught a carp on the Orvis Full Flex fly rod in Passaic, New Jersey.  I hooked eight carp
but only landed one.  I don't know why this happened.  At first I thought it might have been
because I used too small of a hook size( #14).

I tried a larger hook size.  And I lost what felt like a big carp (he ran from one end of the lake to the other).  It seemed that my hook set was good .  I fought the fish no different from other fish I' ve landed in the past.  Could it be the rod?  This rod is old but it has caught a lot of fish.

What is odd about losing the fish was I landed one and then proceeded to lose a few more.