Yeast Starter

I have done yeast starters for my last couple of batches. I have been using liquid yeast. Last night I did another one but the airlock is not moving or has any type of activity(i.e. bubbles), but there is a lot of foam at the top of the wort. Any reason for this happening? Any ideas on how to fix without redoing the yeast starter? Thanks for the help.

How much extract did you use and what is the starter volume? After you cooled the wort and pitched, did you shake the HELL out of the container for at least 2 minutes? When you boil the water, all of the oxygen is forced out. Yeast need this oxygen to get started with fermentation quickly. Wort with no oxygen can lead to long lag times and incomplete fermentation. My suggestion is to grab the container now and shake it up... and wait another day. If there is live yeast and fermentable sugar in there, it will ferment, eventually. What temperature did you pitch the yeast at? Also, check to make the container is not leaking CO2 somewhere.

I areated the wort before putting it into the jar. I will check for CO2 leaks. Thanks.

if you didn't use much extract, you may not see activity. If you use glass, look to see if there is a yeast colony settling at the bottom into a cake

I never see any activity when I make a starter, just cloudiness which indicates some yeast are doing their thing.

If you have foam, my guess is you have fermemtation and the lack of bubbles is due to a loose seal.