Decision-state and empty string test

amy

i'm using a decision-state tag to find out if a form input string is empty or notCode:
lt;decision-state id=quot;isfieldEmptyquot;gt;
lt;if test=quot;${flowScope.searchCommand.field != ''}quot; then=quot;displayResultsquot;
else=quot;displayResultsEmptyquot; /gt;
lt;/decision-stategt;
this doesn't work. What should i do?

thanx