Fix / Edit Build.Prop Help !?

[Warlock-Weary]

Fix / Edit Build.Prop ?
Seems I have to edit the build.prop to add / change net setting ..
I am using .. ES File Explorer to edit the file ..
I have used this on a different Build .. and it worked fine.

I believe in the build.prop you have to change the
net.ppp0.dns1 and net.dns1 to 10.177.0.34
for the T-Mobile apps to work like visual voicemail etc

net.ppp0.dns1=10.177.0.34
net.ppp0.dns2=10.162.130.84
net.ppp0.dns3=10.177.0.34
net.ppp0.dns4=10.162.130.84

But everytime I do It refuses to boot .. after the changes ..
I Really Want .. t-mobile Usa visual voicemail working!

Any Suggestions ? Help ? I Could Try!