Should this mod work on 1.2.3 and if so why i get this error
FINE: Failed to load mod from "mod_IC2Thermometer.class"
2012-3-23 16:14:27 ModLoader addMod
FINER: THROW
java.lang.NoClassDefFoundError: forge/IUseItemFirst
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(Unknown Source)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Unknown Source)
at java.lang.Class.getDeclaredFields(Unknown Source)
at ModLoader.setupProperties(ModLoader.java:1720)
at ModLoader.addMod(ModLoader.java:292)
at ModLoader.readFromModFolder(ModLoader.java:1283)
at ModLoader.init(ModLoader.java:886)
at ModLoader.addAllRenderers(ModLoader.java:186)
at aho.<init>(aho.java:79)
at aho.<clinit>(aho.java:9)
at net.minecraft.client.Minecraft.a(Minecraft.java:395)
at net.minecraft.client.Minecraft.run(Minecraft.java:732)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: forge.IUseItemFirst
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 24 more
can someone help ?