Eruv Tavshilin on Bread Only

  I made an Eruv Tavshilin with a blessing on bread only, is that sufficient?

It is not sufficient, and you need to make an Eruv Tavshilin again on bread only, and say 'behadin tavshila', but do not bless again.

Gemara Beitza, page 15: "Beit Shammai say: two dishes, and Beit Hillel say: one dish. And in the Gemara it is said, 'That which you bake, bake, and that which you cook, cook' — from here Rabbi Elazar said: one cannot bake except on what is baked, and one cannot cook except on what is cooked. From here the sages derived the Eruv Tavshilin from the Torah. And Rabbeinu Tam wrote in Sefer HaYashar that it implies that although Beit Shammai holds that one dish is needed, nevertheless, the cooked does not permit baking, and the baked does not permit cooking. However, R"I disagrees with him because in the Jerusalem Talmud, Tractate Beitza, Chapter 2, it is said: 'That which you bake, bake, and that which you cook, cook' — Rabbi Elazar says one bakes on what is baked and cooks on what is cooked, Rabbi Yehoshua says one bakes and cooks on what is cooked. What is the reason of Rabbi Elazar? 'That which you bake, bake, and that which you cook, cook'. What is the reason of Rabbi Yehoshua? 'That which you bake, and that which you cook, cook'. And since Rabbi Elazar is a Shamutai, and the law is not like him, one dish is sufficient. L"M ruled in Shulchan Aruch, Siman 527, that both a dish and bread are needed.

And therefore there is no side in the Gemara that only baked is sufficient, and nevertheless, one does not bless due to SBL, which Shaarei Tzedek brought in SK 18, that according to the opinions of the early ones, the cooked permits cooking, and the baked permits baking, therefore the Eruv Tavshilin at least permits bread, and since one blessed once on a good Eruv Tavshilin, one cannot bless again on an Eruv Tavshilin that completes the first.