Hello Sandhya,
You need to set different Conversion status flags for Hiragana and katakana.


For Hiragana set flag as
IME_CMODE_JAPANESE | IME_CMODE_FULLSHAPE

For katakana set flag value as
IME_CMODE_NATIVE | IME_CMODE_KATAKANA


And in ImmSetConversionStatus() set this flag value


rgds
Vinod