The upgrade weapons from Xur is designed for Exotics that were earned before the expansion "The Dark Below" launched. Exotics acquired after that are automatically the 2.0 version.
You can check the FAQ on Exotic Upgrades for details.
[url]http://www.bungie.net/7_Exotic-Upgrade-FAQ/en/Help/Article/12457[/url]
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Ok because I bought the helmet from xur last week and I needed the exotic shard to do the last upgrade bubble