Probe Problem

[dau]

Hello,
I'm having problems with my self-built measuring device.
The input stage looks like this:

1V ------3M6-----------n.inv. amplifier x1,6------- 1V
| |
1,125M 5M4
| |
GND GND

When I connect a x1/x10 probe I get with 1V/10V applied to the tip 1V +-3mV at the output of the amp.
x1/x10 probe:

<-------9M---------->
| |
|__--____|


When I connect a x10/x100 probe I get with 10V at the tip and x10-range 0,987V?

x10/x100 probe (only x10 range shown):


<----4,49M--------->
|
|
0,969M
|
GND

Why are the results so different?

 

[dau]

Hello again,
I've almost solved my problem
The 987mV is exactly the calculated result for the x10/x100 probe with 1MOhm input resistance.
To get 1000mV the 969k should be 976k or the 4,494M a little bit lower.
I don't know the real values, does anyone?
My biggest problem is:
Can I change the probe values by opening it without destruction?
And who delivers x10/x100 probes?
Thank you