I dont think either of those blades are correct. They are both ripping blades for a table saw. What blade came with the saw and what brand of saw do you have. Try to find a cross cut blade or one that is designed for a miter saw.
Here is a link to a few blades for a miter saw.
http://www.amazon.com/s/ref=nb_ss?url=search-alias=tools&field-keywords=12"+miter+saw+blade
Here is a link to a few blades for a miter saw.
http://www.amazon.com/s/ref=nb_ss?url=search-alias=tools&field-keywords=12"+miter+saw+blade