I think u tried to buy it yesterday. by 09 02 hrs this share had already reached it limit of 5 percent for the day. there were no sellers only buyers,. that is the reason why you could not get these shares. nothing wrong with sbi site.
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Ok let me tell you-Some of those shares whose weekly/ 10 days average TRADING Volume is less than 5000 you are allowed only t oSell and no tallowed to buy in that basket
You can call ur Trading company (Say MOSL ) and ask them to put in your Bids for buy-In any case same day u can not Sell at higher rate and then buy at a lower rate.
U r only allowed t osell Clear now
U can see that list from your pull down menu There are man yshares falling in tha tcategory due to low floating stocks