How are we related???
The next time you're searching your list of matches, and you say to yourself.... I don't see any names I recognize, look at this chart....
1st cousins share a grandparent, (you have 4 of them on your tree they have 4 on their tree)
2nd cousins share a great-grand, (you have 8 of them on your tree they have 8 on their tree)
3rd cousins share a 2x great grand, (you have 16 of them on your tree they have 16 on their tree)
4th cousins share a 3x great grand (you have 32 of them on your tree they have 32 on their tree)
Now we have 32 3x great grands (with no tree collapse) That's 32 different surnames you could have in common with your DNA match. IF you have all 32 names of your 3rd great grands, and they have all 32 of their 3rd great grands.
Do you have all 32 of your 3x great grands names??
What about all their children's married names? do you have those names too?Now we all know most of our 3x great grands had 6-13 plus kids...and every female would have married adding another surname to look at on each of the 32 common names. So the list of surnames will grow by 1 for every female born to every generation. Let's say our common ancestor (3x ggp) only had girls, 10 of them (that's 10 different surnames) ... and then those girls (2x ggp) had 10 girls,(10 more surnames) Then those girls (ggp) had 10 girls (10 more surnames) We now have 30 different surnames just to get to ONE of our 32 different 3x ggp.
So, If you only have your direct line researched and none of their siblings researched, you may not see a matching name.
I'm not saying do extensive research on every child of every grandparent (although it can help) but you should at least list the names of all the children in every marriage, and who they married, so when Mr John Jacob Jingleheimer Schmidt shows up as your 4th cousin, and you look at his tree and your tree, you can easily see that his name Schmidt was the married name of your 3rd great grandmother's oldest daughter's daughter, and you come from her youngest daughter's daughter.