Yeah, previews are always nice. At least you included them in the database.
But...they're not going to work.
First, they are the wrong size. All tech icons must be 128x128 pixels for a large and 32x32 for the small. I only downloaded stone tools but the large icon is 83x116 (the small icon is 32x32 as necessary). They are both indexed as required but both are missing two important colors at the end (or beginning depending on the program) these are a bright green which has an RGB (Red, Green, Blue) value of 0,255,0 (or an HTML code of 00ff00) and a fuchsia with an RGB of 255,0,255 (255 is max) or an HTML code of ff00ff. These two colors can easily be added to the end of the palette in the order I said them (first green, then fuchsia) but first you you need to re-index them to just 254 colors so you can then add the 2 more at slots 254 and 255 to give you 256 colors (0 counts as a slot). This can be accomplished by converting to millions of colors and then re-indexing to 254 as mentioned above. Oh, and one last thing, by doing the aforementioned you get a much better quality image, I'm not really sure how you got the palette you did..maybe you applied one you found somewhere else? Anyway, its surprising how good an image can look with just 256 colors but you have to have all of the colors in the palette, as it is most (from what I can tell) of the colors are never used.
If all of this is confusing don't get discouraged! The process may sound complicated but it really isn't all that hard. I'm sure there are tutorials in the (where else?) tutorials forum that will explain this too.
edit, if you have questions it would probably be good to mention which program you're using to make these.
