Default [Q] error this application need -> busybox<-

hi fnds mine is micromax a110 phone. in that i've flashed custom rom ultimate galaxy v2, & it is running very nicely . now d problem is just i want to increase my ram. for that i'm using roeh ram expander apk file.it is installed, but when i'm opening it it is showing like "Error! This application need -> busybox<- Application exit now" i've installed busybox already but still it is showing same error
so pls help me fnds how 2 overcome this problem.
all d thing i want is to increas my ram so if any possible way for this, it will be more appreciated.
thanks alot in advance