FitNesse - Drop down field value selection fails

Hi,
I'm facing the issue to populate values in a drop-down field via FitNesse script .

This is working fine for me up to 10 values in drop down, but failing to set the other values.
Assume that my drop-down has 15 values, I'm able to populate that field using the above script for first 10 values in drop-down, but the same doesn't work for rest of the values to be populated(from 11 to 15) in drop-down.

Please let me know if any solution available for the same