Hi user,
Please check job log details form ecc system.
go to bw server, RSA1, go to respective Info package, from menu environment--> Job overview --> in the source system, click on it, it ill prompt for ecc user id and password, enter those, its take you to SM37, select displayed job and click on Job log details. please see it may say where its causing or share here.
During your load at ECC side some one modifying the data, so thats your load may disturbed. delete psa request and try run now and check it.
Thanks