user exit for me31l ( scheduling agreement )

hi all,

i am using transaction me31l to create scheduling agreement .

but while entering item details , i want to check the availability of bom for material entered .

if the material has bom , i want to continue with the process other wise it should pop up an error messsage. the field material displayed on the screen is of type ekpo-ematn .

let me know if any way to do it.

please help me out.

srinivas manai.