The attribute indices takes index, respectively indices of attributes whose values you wish convert to word vector. So you have two attributes class with index 1 and text with index 2. Setting first-last takes both and very likely did nothing with class since it is usually single value, and make a word vector from attribute text.
Cut to the chase, your only options in this case is to use 2 or first-last, but result will be the same. 500 is out of range since you have only 2 attributes.
PS. If you wish use just range of words from obtained word vector, you can use Remove filter and specify indices of columns (words) you wish to remove...