Friend, i guess the user make it a little mess, but it worked for me, so i would like to put it more clear:
Select NroCongresista,Format(Sum(TipodeMovimiento*Fecha),"Long Time") from MovimientosTable group by NroCongresista;
this, return this:
NroCongresista Expr1001
293 12:03:43 AM
294 12:00:04 AM
it , may sound confusing, but if u check this:
ID ParticipantesTableId NroCongresista TipodeMovimiento Descripcion Fecha
109 1 293 -1 SISTEMA 4/30/2006 2:40:32 AM
108 1 293 1 Entrada 4/30/2006 2:36:52 AM
105 1 293 -1 Salida 4/30/2006 2:36:42 AM
104 1 293 1 Entrada 4/30/2006 2:36:39 AM
107 11 294 -1 Salida 4/30/2006 2:36:51 AM
106 11 294 1 Entrada 4/30/2006 2:36:47 AM
there are, just the right values.
Resuming: it calculates the time, enlapsed for each case: 293, 294. - which are exactly: 3 minutes and 43 seconds, and 3 seconds for the other.
i wish it helps you