Excuse me?

I don't know a whole lot about robbing a store, but I'm sure speaking clearly helps:

Volusia County sheriff's deputies said Carlie McDuffie, 24, walked into a Family Dollar store and told an employee to hand over money from the register in a quiet voice that the clerk either didn't hear or didn't understand, the Orlando Sentinel reported Thursday.

Sheriff's spokesman Brandon Haught said the 34-year-old clerk asked McDuffie what he needed and the suspect repeated the demand in the same whispered tone. The clerk again asked what he needed, and McDuffie said "forget it" and left the store, Haught said.

The cops arrested him half an hour later after the clerk realized that he was trying to rob the place, but I think he has a decent defense. I mean, how can the clerk testify that he was trying to rob the place when he or she couldn't initially figure out what was going on?