Can I modify a controller from the MATLAB library in Simulink?

I am trying to work on a pre-existing PLL Simulink Controller. I want to implement a few changes to it, but if I insert anything inside the mask, I get an error that says "Initialization commands cannot be evaluated". I read somewhere that if I make changes under the mask, then "i am on my own", but is there really no way of making changes to a pre-existing MATLAB library controller?

Answer 1

[Jose Lara]

Emilija, there are some blocks that you can edit after disabling links from the libraries. The error you are experiencing may caused due to a change in a variable/parameter that was required in a callback function or initialization of the block. Since you are editing this block, you will have to check each callback and masked variables to find the source of the problem.