If in SCI FIFO interrupt not having any effect

Hi Folks

I have a piece of code that uses the SCI FIFOs on the F2827PT.

It includes a ISR for the transmit interrupt. Inside this ISR I check a global Uint16 variable for 0 or 1 with an if statement

However whether I check (myVar !=0) or (myVar==1) the statements with in th eif statement are ALWAYS executed.

I have tried:

if (myVar != 0) {

//do something

}

have also tried:

if (myVar == 0) {

//do something

}

have also tried:

if (myVar != 0) {

//do nothing

} else {

//do something

}

and also:

if (myVar == 0) {

//do nothing

} else {

//do something

}

Whatever I do the control ALWAYS reaches the "//do something"... Is there some gotcha for checking vars with if's in ISRs that im missing??

Ta