diff --git a/langgraph_swarm/swarm.py b/langgraph_swarm/swarm.py
index d389d4b..8738b82 100644
--- a/langgraph_swarm/swarm.py
+++ b/langgraph_swarm/swarm.py
@@ -127,8 +127,8 @@ def add(a: int, b: int) -> int:
         ```
 
     """
-    channels = builder.schemas[builder.state_schema]
-    if "active_agent" not in channels:
+    #channels = builder.schemas[builder.state_schema]
+    if "active_agent" not in builder.channels:
         msg = "Missing required key 'active_agent' in in builder's state_schema"
         raise ValueError(msg)
 
diff --git a/pyproject.toml b/pyproject.toml
index 66ca0b3..7217ec4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,8 +14,10 @@ license-files = ["LICENSE"]
 readme = "README.md"
 requires-python = ">=3.10"
 dependencies = [
+
     "langgraph>=0.6.0,<2",
-    "langchain-core>=0.3.40,<0.4.0"
+    "langchain-core>=0.3.40,<2.0.0"
+
 ]
 
 [dependency-groups]