WriteProcessMemory with same address.

Hi

I have created a main application which do the following thing:

1. OpenProcess Function (Let's say we open "calc.exe").
2. VirtualAllocEx Function (Allocate some bytes in "calc.exe" memory).
3. WriteProcessMemory Function (Write some bytes in "calc.exe")
4. CloseHandle

Then I try to do the the same thing again with the same instance of "calc.exe".
But this time I know the allocated memory address from the last time so I only need to do the following thing:

1. OpenProcess Function (Same instance).
2. WriteProcessMemory Function (Write some bytes. I know the address from before)
3. CloseHandle

Why is this not posible?
I get an error when I second time tries to write in the same memory address