You can easily check whether you have connected the active document with a TM or not, and how it will be accessed. Simply execute menu command MetaTexis | Translation memory (TU) | Automation options. If any TM is connected to the document, it is displayed in a grey text box (Main translation memory) in the upper frame of the dialog. (If this is not true, go to the document options and select or create a main TM).
Now look at the automation settings for the TM in the Automation options dialog. To have leverage effects in a document, both automation options need to be checked (automatic saving and automatic searching). Then click OK.
As a final step, you have to save the segments already translated in the main TM by clicking on menu command MetaTexis | Translation memory (TM) | Save all translated segments in main TM.
Now, check whether the language settings of your document are correct. If this is so, go to the Database center (click menu command MetaTexis | Translation memory (TU) | Display main TM) and check whether the language settings for the TUs in the TM are correct. The languages in the TM must be the same as the languages of the document currently translated.
After you have done this, you should be able to see leverage effects (if any!).