```
data4 = {{"050318", "111529"}}

Do[
 ID2 = data4[[i, 2]];
 s = Import["http://www.swift.ac.uk/xrt_curves/00" <> ID2, "Text"];
 s = StringSplit[s, "\n"];
 line = Position[s, "Flux Light Curve"],
 {i, 1, Length[data4]}]

```

The `StringSplit` works properly, but when I want to identify the position it gives
line `{}` empty
I expect instead a number like
`{{106}}` for example

Even when I try with 

```
Do[
 ID2 = data4[[i, 2]];
 s = Import["http://www.swift.ac.uk/xrt_curves/00" <> ID2, "Text"];
 s = StringSplit[s, "\n"];
 line = StringPosition[s, "Flux Light Curve"],
  {i, 1, Length[data4]}]

```

it gives me not a single line, but many empty ones.