ReportingServices2010.GetItemDatasources(string localPath) issue giving 260 char or other error

Hi,

I am using the following code to Get and Set the ItemDataSources but getting 260 char error or likewise. Please help me where I might be making mistake. 

 //Get Data set from the Item
 ReportingServices2010.DataSource[] ds = null;
string ItemPath = @"C:\Users\pareea\Downloads\Attribution Detail.rdl";
ds = rs.GetItemDataSources(ItemPath);

 //Set the Dataset for the item
 rs.SetItemDataSources("/Performance/Attribution Reports/CopiedEmployeeReport", ds); 

Kindly help me in this regard.

Ankit