Problem when attaching material to network

Hiii Experts,

Need ur help.I am attaching material to a network and saving it.Till this point it is okay, but when i am trying to open the project again it is showing me the error

Express document "update was terminated" received from author" --- common display user

Error info... 00 671: ABAP/4 processor: SAPSQL_ARRAY_INSERT_DUPREC

and material is not getting attached.

Please help me to solve it.

Regards

Brijesh Pandey