Error in formulating piecewise linear constraints with two subsets

[r.ilma...@gmail.com]

Dear All,

 I am currently dealing with facility location - allocation problem for and thus, formulating a piecewise linear constraints using two subsets, node and vehicles. Below is my code:

However, it resulted in the following error:

I have tried to look around in the web and also tried to tweak the code, but it seems will not work well. Does anybody have any ideas why this happenned?

Thank you in advance