RH 7 Click Link to Frameset and Topic Opens Full Screen

I am using RH 7 and am revising a project originally created using RH5 (in 2006). I have several links to a frameset in my project; these links are in my Related Topics list in several topics. When I compile and click the links, some of the linked to topics open as they should with the TOC panel on left of screen and topic on the right, but others when clicked open the topic in full screen. To create the links, in each instance I list the topic name under Related Topics, highlight it and drag the frameset icon to it; then I double click the link and on the Hyperlink dialog/Hyperlink Options select "Display in Parent Frame" and click OK. Although all of these links are created exactly the same way, three of them (when clicked) display the full screen of the frameset topic and I lose the left panel TOC. I have looked at the HTML code for each and for 2 topics in which link isn't working properly the following is the HTML for each: (topic 1)<p class=RelatedTopicsList><a HREF="../List_of_Codes.htm" target=_parent>Enrollment
Codes</a></p> (topic 2)<p class=RelatedTopicsList><a HREF="../List_of_Codes.htm" target=_parent>Enrollment
Codes</a></p> But for the topic in which clicking the link displays the topic in right panel and TOC in left, here is the code for this (topic 3). Note that the Hyperlink Option selection is "Page Default"; when I changed the Hyperlink Option in topic 1 to "Page Default" it still opened the topic full screen.
<p class=RelatedTopicsList><a href="../List_of_Codes.htm">Enrollment Codes</a></p> I need help in trying to correct this problem--if it is possible to correct.