Does the "---" appear when the references happen to be by the same author(s) - also known as "repeated authors"? If so, it sounds like the "Replace repeated authors with: ---" option might have been mistakenly selected. Check/change the "For Subsequent Works by the Same Author" setting located in the "Author Lists" option on the output style's Bibliography setting":
1. Go to the EndNote toolbar, select EDIT, OUTPUT STYLES, EDIT [Name of style]. This will cause the output style's main window to pop-up.
2. In the left column of the style window, locate "Bibliography" and click to select AUTHOR LISTS.
3. On the right side, bottom, locate the selection labeled: For Subsequent Works by the Same Author. If the last option is selected (Replace repeated authors with: ---), change to: Print the author list as defined above.
Close the output style window. If prompted to save the changes, note that they will be saved under a new file name that includes the word "Copy" (unless you manually delete the word). If you save the changes as a copy remember to change the style selection in EndNote and your word processor to reflect the proper output style name otherwise the changes won't apply to your document.
How is the space between characters determined? Each character is associated with a virtual rectangle, and when two characters are typeset beside each other their rectangles are aligned. (Think of fitting together blocks of lead type.) If the rectangle for every character were just large enough to contain the character, this method would result in inappropriate spaces between adjacent characters. For example, an "o" and an "e" would touch each other, whereas a significant space would exist between an italic "f" and an italic "l" (because the top of the "f" would be aligned with the bottom of the "l"). This problem is addressed by specifying the rectangle associated with each character to be different, in general, from the smallest rectangle that contains the character. For some characters, like "o" and "e", the rectangle is wider than the characters, and for other characters, like italic "f" and "l", it is narrower. The distances between the edges of the rectangle and the edges of the character are called "sidebearings". Thus for "o" and "e", the sidebearings are positive; for italic "f" and "l", they are negative.
Adding sidebearings to the characters does not allow for perfect spacing between characters. In a font with n characters, there are n2 pairs of characters, and potentially the optimal space between the members of any given pair is unrelated to the space between the members of any other pair. However, it isn't possible to generate n2 arbitrary spaces from the 2n sidebearings specified by the font. (Even for n = 2, when n2 = 2n, generating optimal spacing from a sidebearing specification may not be possible. Try specifying appropriate sidebearings for a font consisting only of "/" and "\" so that "//" and "\\" are close together and "/\" and "\/" do not bump, for example.)
Nevertheless, the method works fairly well most of the time. In only a few cases is intervention required. An example is the case of a sloping character followed by an upright character (or by a space and then an upright character). In this case, the space between the characters is typically too small. (Try typesetting .) To deal with this problem, each character in a font comes with an italic correction, obtained by typing after the character. The idea is that when switching from a sloping character to an upright one, you add this correction. For example, instead of typing , you type . Or, more realistically, instead of typing , you type .
The good news is that if you use to produce italics, you don't have to worry much about the correction, because takes care of it most of the time. The bad news is that doesn't take care of it all the time, and in some situations you may not realize that you are switching from a sloping font to an upright one.
The italic correction is omitted by before a comma or a period, as it should be. But what about ? In this case adds the correction, even though doing so seems inappropriate; a correction can be avoided by typing . In other similar cases you may need to specify .
Here's a situation in which you may not realize that you are switching from a sloping font to an upright one: suppose your theorem environment sets the text in italics and you type
Then you need more space after "If", and adding an italic correction () improves the appearance. However, that's not quite the end of the story, as this discussion shows.
The bottom line: use to produce italics, and be aware that in a few cases you may need suppress the italic correction; in theorems, consider adding an italic correction between text and math, although there may still be room for improvement in the resulting spacing.