As bowhunter mentioned, the strike will always come when you're not
watching. Indicator fishing is an art similar to checking out Womens Breasts, you can't sit staring directly at it or nothing good will happen. You must develope your
perhiperal vision, so you appear to be watching the ducks. The strike WILL come.

Another trick you must master is the slip strike. Hold the line loosely
between two fingers while you're waiting. When the indicator goes down,
strike immediately, but let the line slip.

Depth of your fly is critical as is a vertical presentation, normally
a foot to 18" above the bottom or weed layer is
effective, but you may need to vary that. If surface activity is great fish the
surface film with a floater that hangs vertical. (there's a pattern for that).
An electronic depth finder or Polish depth finder is a must to set your depth.

Not all lakes are good chrionomid lakes and not all parts of good lakes are
good chironomiding. Most activity will be found at any one time in a narrow
depth band starting around 3-6 feet in early spring and moving outward to
12-15' as water warms and the sun angle increases. Your job each day is to find the most active area of the lake and most active depth by prospecting. Look for broad flats of gradual bottom taper from 5' to 15' depths with muddy bottom and short weed cover.
Bathometric maps are a big plus in "finding honey holes"

Good luck and don't give up. It's not rocket science but requires some experience and
patience. You can learn most rapidly by going with good chironomiders or going where
they fish and observing etc.