As with brewing, technique is critical to frothing well. Frothing is very sensitive to technique, which has a steep learning curve. If the machine is producing steam then an adjustment to technique may need to be made. The video below shows proper frothing technique.
How to Froth and Steam Milk for Latte Art, Cappuccino and More
Many frothing mistakes are common missteps that result in poor or no froth. The video below identifies these mistakes and shows how to correct them.
Quick Tip: Six Common Milk Frothing Mistakes
It is also important not to overheat your milk. The milk will have the sweetest and most velvety texture between 140-150 F°. As you froth past this point the milk will lose its sweetness, the froth will take on a gummier texture, and eventually the milk will scald and begin to taste burnt. The video below explains how to use a frothing thermometer so that the milk is kept within the ideal range.
How to Use a Thermometer When Frothing Milk for Latte and Cappuccino