Hi,
I guess that you are working with LoadRunner 11. Do you have any patches installed?
In LR 11.03 and LR 11.04 you should have the option to add an else in the “if block” step.
You can check what patches are available for LoadRunner 11 and the order they should be installed in the following link:
http://support.openview.hp.com/selfsolve/document/KM1088847
Kind regards,