problem in simulannealbnd optimization

hi i have these two function(@input and @err) for obtaining minimum value of error . i put @input in function object of simulannealbnd algorithm and @err in output function of it but i get this error

Optimization running.
Error running optimization.
Output argument "F" (and maybe others) not assigned during call to "err".

can any one tell me how solve this error or how to connect function output to optimization ?!

[Walter Roberson]

You did not post the code