How to assign value in the Data Table assign action?

If I assign value in the Data Table it display the variable name along with $ instead of variable value.

1. This is my flow.

   

2. Assigning ‘Hi’ string value to the samplestring variable.
3. Then assigning the string variable to data table
4. the the value is displayed.
5. But the output contain only the variable name.
6. Do I need to change anything?