Share 'String to path conversion'

As always I am missing some secret magic something somewhere, I have been trying to recreate khabazi's jaquard weave in grasshopper, and everything is fine until I have to connect the f(a,b,c,d,x)= a&b&c&d&x) to the p input of a branch - the error message states that the convertion from string to path has failed... any help please?   I have attached a partial screenshot and part o…