fene bond

I still have problem with FENE bond. I defined sphere’s diameter=0.5 and R0=2.0.
I faced the same error as i showed in the following:

*Bond atoms %d %d missing on proc %d at step*
*But when i changed value of R0 or diameter a little lower or higher than thier previous values , error message changed to bad fene bond. I changed bond style. I do not know what i should do to solve this problem. I need to your guidance. Please help me*
*Thank you in advance;*