Determining viability of a yeast starter?

I made a yeast starter on Thursday from a White Labs Abbey Ale, 2.7 quarts of water, and 9 ounces of DME. Temps have been between 70-76 the whole time. Not sure of the date on the yeast vial since the ink was smudged, but I bought it from my LBHS the same day I made the starter. Since then there is zero visible activity. This is just my second time making a starter, but my previous one had visible krausen on the surface after just one day. I'm making a fairly high gravity Belgian ale so I really need to know if this puppy is active or if I need to go buy another tube of yeast. Help!

Usually there will be some kind of bubbling up the sides or krausen on the top. If there has been no sign of CO2 being produced it might not be very healthy. Take a gravity reading of the starter wort, if it has dropped you know you just missed the activity, if it is still around where it started it's time to go get a new vial.

Well, I left the house for a few hours to run some errands and there appears to be some activity finally. I may have to delay my brew plans by a day, but at least it appears to be waking up now.