if condition returning different values on different environments

Question

'i am having 3 string variables.'

String x, y, z;

after db call variables are set to

x=    ; (blank)
y=null;
z=null;

after ternary condition

x=  ; (blank) 
y=no_value;
z=no_value;

then followed by if condition

 if(!x.equals("no_value"))
{
print 1st;
return;
}

if((y.equals("no_value") && (z.equals("no_value"))
{
print 2nd;
return;
}

'In my eclipse on windows OS with Tomcat it is working fine (checked on 2 systems) executing the 2nd if condition.

But after deploying to the application server (IBM web sphere on Solaris OS) it is executing the 1st if condition. (also checked on two different servers)

I guess its because of the other work all ready deployed on to the server(my work is a addition to existing application).

But what really wonders me is that as i am sure and also cross checked the inputs before the if conditions and sure of the variables being same on both environments. But how can one get two different outputs with same inputs & same logic ?'