Did you just post this: https://answers.launchpad.net/r6rs-libraries/+question/98600
If so, you will probably find a better answer there.
The likely cause is the environment. You will need to have all the required libraries loading in the interaction-environment for this to work.
To 'ungensym' a gensym:
> (ungensym 'g$a$2554$1Hr@99)
Basically, between the first and second $ is the name token, the second token is just an incremented index, while the third is a timestamp. This all is needed to create truly unique gensyms that works over multiple sessions.
Some may not work, as they are just temporaries.