Problem adding a float to a DoubleVar

[nortski]

I have declared a DoubleVar() as I need to use the variable as a textvariable for a tkinter label. However; when I try to add to it I get the error

Output:
unsupported operand type(s) for +: 'DoubleVar' and 'float'

This code is part of a function:

global dailyTotal
    dailyTotal = dailyTotal + 3.0

And dailyTotal is decalred as a DoubleVar():

dailyTotal = DoubleVar()
    dailyTotalLabel = Label(root, textvariable = dailyTotal)

[Gribouillis]

Use

dailyTotal.set(dailyTotal.get() + 3.0)

[nortski]

Use

dailyTotal.set(dailyTotal.get() + 3.0)

Thank you, that did the trick.