BOM issue

Hi

I have created 2 boms altnative1 and 2 for ..finished product....both are acteive

i have create Subcontract P.O for Finished product ... in P.O cilk master data and explode BOM... but her system... always taken compontes bydefault from alternative 1...BOM....

some time i want to use altrnative 2... frquently changed ..BOM ..

so alest system should display both alternative when click the BOM explode... but in my case system does not ask .. directly taken altnative 1 bom

so here always remove the components... and reentered...components.. whichare mention in altna 2 bom...

can any one body help me in this issue..

regards

sesidhar