optim: abnormal termination in lnsrch

I'm using optim() to minimize a certain function.
Often the minimization ends with the message:
ERROR: ABNORMAL_TERMINATION_IN_LNSRCH

What is optim() trying to say?
What have I to change in my function to make the minimization succeed?
Do you think using BBoptim() instead of optim() changes anything?

Thanks for your help!
			mario

Ing. Mario Valle
Data Analysis and Visualization Group            | 
http://www.cscs.ch/~mvalle
Swiss National Supercomputing Centre (CSCS)      | Tel:  +41 (91) 610.82.60
v. Cantonale Galleria 2, 6928 Manno, Switzerland | Fax:  +41 (91) 610.82.82