Access Denied when load a Crystal Report

Hi!

First, an apologize for my english not is very good.

my problem is a little strange, because is not recurrent only sometimes appear a error that said:

"Access Denied, Load Report Failed"

my code is this:

Dim ds As DataSet
        Dim dt As DataTable = Nothing
        dt = New dsReportes.resumen_semanalDataTable
        Try
            query = sqlReporteResumenSemanal.sp_cp_reporte_resumen_semanal("D_Recurso_Semana", dropSemanas_ini.SelectedValue.Split("-")(0), dropSemanas_ini.SelectedValue.Split("-")(1), dropSemanas_ini.SelectedValue.Split("-")(2), dropSemanas_fin.SelectedValue.Split("-")(0), dropSemanas_fin.SelectedValue.Split("-")(1), dropSemanas_fin.SelectedValue.Split("-")(2), Master.UserID, dropAnalistas.SelectedValue, Master.UserArea)
            ds = AccesoDatos.LoadDataSet(query)
            lblArea.Text = ds.Tables(0).Rows(0).Item("Area")
            lblSemana_ini.Text = ds.Tables(0).Rows(0).Item("Periodo_ini")
            lblSemanas_fin.Text = ds.Tables(0).Rows(0).Item("Periodo_fin")

            dt = ds.Tables(1)
            crSource.Report.FileName = "Reportes\rptResumenSemanal.rpt"
            crSource.ReportDocument.SetDataSource(dt.DefaultView)
        Catch e As Exception
            Master.ShowError(e.Message)
        End Try

and the exception is in this line:

crSource.ReportDocument.SetDataSource(dt.DefaultView)

thanks for your help!

regards!

P.S. this image show the exception before that i put my code "Try...Catch"

https://drive.google.com/file/d/0B_M1wbQtwa3vQzNxdFFFbmx3emc/edit?usp=sharing