CCS/CC2640: CC2640 simple central uart write issue

Tool/software: Code Composer Studio

I am using a modifed version of simple central. Uart read callback and central init function uart_write works perfectly fine. But when i try to do a uart write in SimpleBLECentral_processRoleEvent the 

case GAP_DEVICE_DISCOVERY_EVENT:

char Sender[3] = {'D','E','V'};
UART_write(uart_handle,Sender,3);

UART write completes but does not return and imprecise error exception handler loop occurs. No breakpoints after thee UART_write work.