I have a simple GridView bound to an objectdatasource. Everything works fine, except when try to do an update I get the following error:
Exception has been thrown by the target of an invocation.

I know from this post that this error might be caused by my stored procedure not returning a value, but my SP returns the Id of the updated row...

I have a trigger on the table I'm trying to update. If disable it, then the update works fine, so I guess the error is related to the fact that I have this trigger on this table. If I try to execute directly my update SP from SQL, with the trigger enabled, it works just fine.

Any ideas? Thanks!

Here's the code of the trigger, it updates some fields based on other fields new values... simple enough

ALTER TRIGGER [dbo].[ChallengeRideInsertUpdate]
   ON  [dbo].[DNN4_ESORV_ChallengeRide]
   AFTER INSERT,UPDATE
AS
BEGIN

 SET NOCOUNT ON;

 DECLARE @Id int

 IF (SELECT COUNT(*) FROM INSERTED) > 0
  SELECT @Id=Id FROM INSERTED
 ELSE
  SELECT @Id=Id FROM UPDATED

 -- CO2
 UPDATE dbo.DNN4_ESORV_ChallengeRide
 SET CO2 = (
  SELECT (UTM.AvgCO2PerKm - CTM.AvgCO2PerKm) * CR.Distance
  FROM dbo.DNN4_ESORV_ChallengeRide CR
  INNER JOIN dbo.DNN4_ESORV_ChallengeTransportationMode AS UTM
   ON CR.UsualTM = UTM.Id
  INNER JOIN dbo.DNN4_ESORV_ChallengeTransportationMode AS CTM
   ON CR.ChallengeTM = CTM.Id
  WHERE CR.Id = @Id
 )
 WHERE Id = @Id

 -- MONEY
 UPDATE dbo.DNN4_ESORV_ChallengeRide
 SET Money = (
  SELECT (UTM.AvgCostPerKm - CTM.AvgCostPerKm) * CR.Distance
  FROM dbo.DNN4_ESORV_ChallengeRide CR
  INNER JOIN dbo.DNN4_ESORV_ChallengeTransportationMode AS UTM
   ON CR.UsualTM = UTM.Id
  INNER JOIN dbo.DNN4_ESORV_ChallengeTransportationMode AS CTM
   ON CR.ChallengeTM = CTM.Id
  WHERE CR.Id = @Id
 )
 WHERE Id = @Id

 -- CALORIES
 UPDATE dbo.DNN4_ESORV_ChallengeRide
 SET Calories = (
  SELECT (CTM.AvgCaloriesPerKm - UTM.AvgCaloriesPerKm) * CR.Distance
  FROM dbo.DNN4_ESORV_ChallengeRide CR
  INNER JOIN dbo.DNN4_ESORV_ChallengeTransportationMode AS UTM
   ON CR.UsualTM = UTM.Id
  INNER JOIN dbo.DNN4_ESORV_ChallengeTransportationMode AS CTM
   ON CR.ChallengeTM = CTM.Id
  WHERE CR.Id = @Id
 )
 WHERE Id = @Id

END