IDL> WHY IS THIS A NULL FILENAME

[winterdead(at)aol.com (WinterDead)]

I am on a windows machine. I am trying to make and anymation. the program that
will not run is readsmd. this program was written by one of my proffesors. it
worked fine on his unix machine but it does not seem to want to run now.
I compiled it but it still wont run. help please
here is an example of my problem: 
IDL> fe=strarr(10)
IDL> fe(0)=('e:99041000')
IDL> fe(1)=('e:99041002')
IDL> fe(2)=('e:99041004')
IDL> fe(3)=('e:99041006')
IDL> fe(4)=('e:99041008')
IDL> fe(5)=('e:99041010')
IDL> fe(6)=('e:99041012')
IDL> fe(7)=('e:99041014')
IDL> fe(8)=('e:99041016')
IDL> fe(9)=('e:99041018')
IDL> fo=strarr(10)
IDL> fo(0)=('e:99041001')
IDL> fo(1)=('e:99041003')
IDL> fo(2)=('e:99041005')
IDL> fo(3)=('e:99041007')
IDL> fo(4)=('e:99041009')
IDL> fo(5)=('e:990410011')
IDL> fo(5)=('e:99041011')
IDL> fo(6)=('e:99041013')
IDL> fo(7)=('e:99041015')
IDL> fo(8)=('e:99041017')
IDL> fo(9)=('e:99041019')
IDL> xinteranimate, set=[512,512,20], /showload
% Compiled module: XINTERANIMATE.
% Compiled module: XREGISTERED.
% Compiled module: CW_ANIMATE.
% Compiled module: CW_BGROUP.
IDL> e=fltarr(512,512,20)
IDL> o=fltarr(512,512,20)
IDL> for k=0,19 do e(*,*,k)=readsmd(fe(k))
% Compiled module: READSMD.
% OPENR: Null filename not allowed.
% Execution halted at:  READSMD             9 C:\RSI\IDL50\readsmd.pro
%                       $MAIN$                 
IDL> .run readsmd
% Procedure was compiled while active: READSMD. Returning.
% Compiled module: READSMD.
IDL> for k=0,19 do e(*,*,k)=readsmd(fe(k))
% OPENR: Null filename not allowed.
% Execution halted at:  READSMD             9 C:\RSI\IDL50\readsmd.pro
%                       $MAIN$                 
IDL> for k=0,19 do e(*,*,k)=readsmd(fe(k))
% Variable is undefined: FE.
% Execution halted at:  READSMD             9 C:\RSI\IDL50\readsmd.pro
%                       $MAIN$                 
IDL> fe=strarr(10)
IDL> for k=0,19 do e(*,*,k)=readsmd(fe(k))
% OPENR: Null filename not allowed.
% Execution halted at:  READSMD             9 C:\RSI\IDL50\readsmd.pro
%                       READSMD             9 C:\RSI\IDL50\readsmd.pro
%                       $MAIN$