Address space overflow and garbage values while using 'sprintf'

Dear all,
The linker gives following error:

*** ERROR L107: ADDRESS SPACE OVERFLOW
    SPACE:   DATA
    SEGMENT: ?DT?TIMER0_ISR?TIMER
    LENGTH:  0002H

I have a global buffer. If i declare it idata then the linker does not give any error. But the sprintf function gives garbage values.
I am unable to understand the problem.

The following is the piece of code:

dtptr = &buff;
strlen = sprintf(dtptr, "%d", PrbTemperature*1000);
UART_TxArray(dtptr, strlen);

PrbTemperature is a float. dtptr, buff[7] and strlen are unsigned char.

kindly assist.