sentence: ; shahzad hasan active : 1986-1998 instruments : bass release contributions : '' vital signs 1 '' ( 1989 ) , '' vital signs 2 '' ( 1991 ) , '' aitebar '' ( 1993 ) , '' hum tum '' ( 1995 ) former members ; nusrat hussain active : 1986-1988 instruments : keyboards , guitars release contributions : '' dil dil pakistan '' ( 1987 ) nusrat hussain is a pakistani singer-songwriter , composer and keyboardist .