You don't say what you are doing to know what may be wrong, but rhubarb in general...

Rhubarb tolerates most soils but grows best on fertile, well-drained soils that are high in organic matter/compost.

Rhubarb is tolerant of soil acidity but does best in slightly to moderately acid soil. 6.0 to 6.8 ph

Responds well to fertilizers. Approx 1 cup per plant of 10-10-10 each spring

A mulch or top dressing the bed with something organic (again, compost, or well composted manure) can be helpful as it helps to conserve moisture, preserves the soil structure, and makes nutrients readily available...don't use fresh. Remove the flower stalks as they appear.

It doesn't do well in hot temperatures and may even go dormant in summer heat - it will at least stop growing until days cool a little if you are regularly having afternoons in the 80's and upwards.

Unless you know otherwise - you may have started with an old piece of rhubarb.

They do need reliable water.

They love to be very well fed - and rotted stableyard manure, or steer manure rotted down with straw or alfalfa will be appreciated. Just keep it back from the actual plant and leave it over the area where the roots are.

When you first make the bed ensure that the soil is deeply dug (about 18" down), has lots of well-rotted compost plus manure stirred through the growing soil, and has no clay pan under which could create a high water table.

The best stems are usually those that come in spring and early summer so you can plan to feed/water to get the stems you're after then. Liquid fertiliser weakly-weekly works well.

ALWAYS leave a few stalks behind so the plant can regenerate.