boundary conditions - invalid value for attribute "node_set"

[dumdidum]

Hi,
I just updated to febio4 (from version 2.9.1) and am trying to rewrite my feb input files but get the error invalid value for attribute "node_set".
Here is how I defined the node set in the mesh section:

<NodeSet name="lig-cart-fib">
8328,8387,8399,8327,8377,8341,8363,8407
</NodeSet>​

And here is my boundary definition:

<Boundary>
<bc type="rigid" node_set="lig-cart-fib">
<rb>9</rb>
</bc>
</Boundary>​

To me thing look just like in the user manual's example code snippets, but maybe I am missing something?