Dear Farzad,

Here someone else has had the same problem which in turn some answers are provided in particular by Dr. Jonathan Knox who is expertise in GIS.

https://groups.google.com/forum/#!topic/arcswat/E9HRyxQbiYc

Hopes you find something.

Best regards,

Majid

Dear Farzad,

You need to have full permission on your project folder. Be sure that all your layers has the same geographic projection and that they cover your full area. You also need to change the regional setting in your computer to USA,  I hope this helps.

Dear Majid,

Dear Gloria,

Thank you for your helpful comments.

I changed the project address to desktop and it works.

Maybe the project should be on the same drive with ARCGIS to work.

Best Wishes

you checked once all the input parameters they should have same geographic projection .

transferring the file to the desktop solved this problem,

Thank you researchers

Dear all Is there someone who can tell me the solution for Error no.91

Error Mmessage: object reference not set to an instance of an object.

module name: msubbains

Function name : Setparameters

Procedure(error line or description): subbasin 8 line: 144

GRID_ CODE=8order by to_node Desc

Please please give me your opinions. waiting in anticipation