Use of C_R(c,t) and C_LIQF(c,t) inside DEFINE_SOURCE
 

I am adding source terms in momentum and energy equation. I am using Solidification/Melting in FLUENT. Whenever I use C_R(c,t) and C_LIQF(c.t) in my UDF, the UDF compiles without any error but when I start the simulation, the simulation crashes with mpt:9999 no error. I think it is because of C_LIQF(c,t). Can someone please tell me about the issue? Any help is appreciated.