The second Modal in my ASPX file doesn’t Post when clicking submit button

I have an ASPX file that contains two modals (myModal and addModal) and a gridview that has buttons calling each of these. I am having trouble with the second modal when opening and clicking its Submit button as it won’t fire a PostBack. Its only a problem with the second one. If I change the sequence of these Modals within the ASPX file, then I again have trouble only with the second one in the file.