Keep getting error property was expecting a com.google.appinventor.components.runtime.TextBox component but got a String instead' while making a gpa calculator

These:

image

are not the components they are the text element of the components. You will find the component block at the bottom of the list of blocks

I am getting this error now.

I think it is here:

image

where to try to multiply Credits with global ScaleValues (which is a list!)