I keep getting this error:

Code:
Microsoft VBScript runtime (0x800A0009)
Subscript out of range: '[number: 1]'
/info.asp, line 79
With this line of code:

Code:
IF (lCase(cStr(fileextension(1))) <> "jpg") AND (lCase(cStr(fileextension(1))) <> "jpeg") AND (lCase(cStr(fileextension(1))) <> "gif") THEN
Can someone please explain why? Thanks!