Let me get to my problem. I just installed a Kenmore Miser 12 Electric 40 Gal H2O Heater
Model #153.321440. I have 120 coming from the breaker into each side of the thermostat (i.e. if I use my voltage meter and touch one lead to a ground and one to the black wire or red wire each gives me 120) but I do not have a combined 240 when I touch one lead to the black wire and one to the red. What is the possible problem? Do you think I did not install the wire correctly at the breaker? Please help!:(

Sounds like somehow you have a breaker onto one hot leg of the panel.

While the breaker should be a 2 pole 240 volt rated, you may have a 2 pole half size, and have it plugged into the same hot leg in the panel. Any 2 pole 240 volt breaker must connect to two bus bar tabs, to get 240 volt.

If you have two single pole breakers opposite each other, this also will give 120 volt per breaker, but not 240 volt, as again it comes from the same bus.

What exactly do you have at the panel. A picture will tell a thousand words.

Thank you for taking the time to send your response, let me see about getting you a picture of the breaker.