diff --git a/light9/web/graph.coffee b/light9/web/graph.coffee
--- a/light9/web/graph.coffee
+++ b/light9/web/graph.coffee
@@ -266,7 +266,7 @@ class window.SyncedGraph
     
     switch objs.size
       when 0
-        throw new Error("no value for "+s+" "+p)
+        throw new Error("no value for "+s.value+" "+p.value)
       when 1
         obj = objs.values().next().value
         return obj
@@ -274,7 +274,7 @@ class window.SyncedGraph
         throw new Error("too many different values: " + JSON.stringify(quads))
 
   floatValue: (s, p) ->
-    key = s + '|' + p
+    key = s.value + '|' + p.value
     hit = @cachedFloatValues.get(key)
     return hit if hit != undefined
     #log('float miss', s, p)
diff --git a/light9/web/rdfdb-synced-graph_test.html b/light9/web/rdfdb-synced-graph_test.html
--- a/light9/web/rdfdb-synced-graph_test.html
+++ b/light9/web/rdfdb-synced-graph_test.html
@@ -27,24 +27,39 @@
      const assert = chai.assert;
      
      describe("rdfdb-synced-graph", () => {
-         let elem;
-         beforeEach(() => {
-             elem = document.querySelector("#graph");
-             window.g = elem;
-             elem.graph.clearGraph();
-         });
-         it("makes a node", () => {
-             assert.equal(elem.tagName, "RDFDB-SYNCED-GRAPH");
-         });
-         it("loads trig", (done) => {
-             elem.graph.loadTrig(`
-                       @prefix : <http://example.com/> .
+       let elem, U;
+       beforeEach(() => {
+         elem = document.querySelector("#graph");
+         window.g = elem;
+         elem.graph.clearGraph();
+         U = elem.graph.Uri.bind(elem.graph);
+       });
+       it("makes a node", () => {
+         assert.equal(elem.tagName, "RDFDB-SYNCED-GRAPH");
+       });
+       it("loads trig", (done) => {
+         elem.graph.loadTrig(`
+                       @prefix : <http://light9.bigasterisk.com/> .
                        :a :b :c :d .
                      `, () => {
-                         assert.equal(elem.graph.quads().length, 1);
-                         done();
+                       assert.equal(elem.graph.quads().length, 1);
+                       done();
                      });
+       });
+       describe("floatValue read call", () => {
+         it("loads two values without confusing them in a cache", (done) => {
+           elem.graph.loadTrig(`
+               @prefix : <http://light9.bigasterisk.com/> .
+               :s :a 1 :g .
+               :s :b 2 :g .
+             `, () => {
+               assert.equal(elem.graph.floatValue(U(":s"), U(":a")), 1);
+               assert.equal(elem.graph.floatValue(U(":s"), U(":b")), 2);
+               assert.equal(elem.graph.floatValue(U(":s"), U(":a")), 1);
+               done();
+             });
          });
+       });
      }); 
      mocha.run();
     </script>