capacitance bridge in order of nanofarad

[soudabeh]

Hello all,
I have a capacitance bridge that the quantity of them is in order of nanofarad.The power supply is a vsin with frequency of 2.5MHz. The problem is that when I connect the power supply to the bridge the voltage of the node connection will become zero.I will become gratefull , if anybody help me.
Thanks in advance.

 

[LvW]

What is your bridge look like (there are several types)?
Why do you need a power supply?
Which node do you mean?
Final question: I cannot count how often we have asked people to present the circuit diagram when they have problems.
I wonder if you can imagine that such a diagram will help us to answer correctly.