Report rendering error in SSRS 2008?

Hi ,

i am trying to export the report to excel from URL , for this i developed URL like below

http://igi-mssql/ReportServer?%2fAggr_Maintenace_Status_Report%2fMaintenance&rs:Command=Render&P1=1&P2:isnull=true&P3:isnull=true&P4=:isnull=true&P5=:isnull=true&P6:isnull=true&P7:isnull=truel&P8:isnull=true&P9=1&P10=10&P11=2&P12:isnull=true&P13:isnull=true&P14:isnull=true&rs:Format=excel

now it is showing the below error

• An error has occurred during report processing. (rsProcessingAborted) Get Online Help
  • Query execution failed for dataset 'DataSet1'. (rsErrorExecutingCommand) Get Online Help
    • Conversion failed when converting date and/or time from character string.  

is there any alternative way to export the reort to excel from  url