The mystery has been solved about why the city’s storm warning system that is supposed to alert residents of approaching danger didn’t sound July 11.According to city administrator Bill Brock during Tuesday night’s Board of Mayor and Aldermen meeting, the radio signal was interrupted because it does not have a dedicated frequency specifically for its use.“The sirens are sent out over the fire department’s radio waves, or signals,” said Brock. “If someone happens to key a mike at the same time someone is punching in the numbers to sound the sirens, the signal can get lost. We didn’t know that happens, but it can happen.