space problem

hi friends.i need ur help.
first i deleted one of my hdd partition of 12 gb.and den i created a new partition of 6 gb and format wid fat32.now d problem dat is remaining 6 gb is being shown as unallocated space and i am not able to convert it in a new logical partition.what should i do now…..
plz help me?????
actually d prob is dat ,on right click the option new partition is not working….