Changing one char of a char array

Using Arduino Programming Questions
1

I am having a problem with this little snippet of code:

    switch (IRvalue) {
      case rem0:
        Serial.println("0 pressed");
        value[pos] = '0';
        IRvalue = remright;
        GLCD.Puts(value);
        break;
      case rem1:
        Serial.println("1 pressed");
        Serial.print("Value : "); Serial.print(value); Serial.print("  at pos : "); Serial.println(pos, DEC); 
        Serial.println(" ");
        Serial.println(" ");
        value[pos] = '1';
        Serial.print("Value : "); Serial.print(value); Serial.print("  at pos : "); Serial.println(pos, DEC); 
        Serial.println(" ");
        Serial.println(" ");
        IRvalue = remright;
        GLCD.Puts(value);
        break;
      case rem2:

In the above code, value is a char array of length 11 and pos is an integer for the current location in an input routine. The value IRvalue is the infra red value coming from the remote.....

Anyway, the line value[pos] = '1'; has the effect of making the array value[] blank !!

2

If the value of "pos" is zero, that's what I would expect.

(well, not actually "blank", but "terminate")

3

This is very strange but it is now working and I have no idea why it didn't last night!