[XeTeX] Beamer in Xelatex

[Nazareth Amlesom Kifle]

Hi,
I am trying to used beamer to typeset Tigrinya text. I get an error  
massage that my fonts are not found, but I know I have the font files  
in place because I can typeset articles and other things in Xelatex.  
My problem is just with beamer.
Do you have an idea of what is causing the problem. The characters  
get printed as ??????


Here is part of the error message I get:



LaTeX Font Info:    Try loading font information for T1 
+TITUSCyberbitBasic(0) o
n input line 136.
LaTeX Font Info:    No file T1TITUSCyberbitBasic(0).fd. on input line  
136.
LaTeX Font Info:    Font shape `T1/TITUSCyberbitBasic(0)/m/n' undefined
(Font)              using `T1/cmr/m/n' instead on input line 136.
Package fontspec Info: Defining font family for "TITUS Cyberbit  
Basic" with opt
ions [] on input line 136.
Package fontspec Info: Could not resolve font TITUS Cyberbit Basic/B  
(it might
not exist) on input line 136.
Package fontspec Info: Could not resolve font TITUS Cyberbit Basic/I  
(it might
not exist) on input line 136.
Package fontspec Info: Could not resolve font TITUS Cyberbit Basic/BI  
(it might
  not exist) on input line 136.
Package fontspec Info: Defining font family for "EthiopicLSU" with  
options [] o
n input line 136.
Package fontspec Info: Could not resolve font EthiopicLSU/B (it might  
not exist
) on input line 136.
Package fontspec Info: Could not resolve font EthiopicLSU/I (it might  
not exist
) on input line 136.
Package fontspec Info: Could not resolve font EthiopicLSU/BI (it  
might not exis
t) on input line 136.
Package fontspec Info: Defining font family for "TITUS Cyberbit  
Basic" with opt
ions [] on input line 136.
Package fontspec Info: Could not resolve font TITUS Cyberbit Basic/B  
(it might
not exist) on input line 136.
Package fontspec Info: Could not resolve font TITUS Cyberbit Basic/I  
(it might
not exist) on input line 136.
Package fontspec Info: Could not resolve font TITUS Cyberbit Basic/BI  
(it might
  not exist) on input line 136.
Package fontspec Info: Defining font family for "EthiopicLSU" with  
options [] o
n input line 136.
Package fontspec Info: Could not resolve font EthiopicLSU/B (it might  
not exist
) on input line 136.
Package fontspec Info: Could not resolve font EthiopicLSU/I (it might  
not exist
) on input line 136.
Package fontspec Info: Could not resolve font EthiopicLSU/BI (it  
might not exis
t) on input line 136.
LaTeX Font Info:    Font shape `T1/lmss/m/it' in size <10.95> not  
available
(Font)              Font shape `T1/lmss/m/sl' tried instead on input  
line 136.

I hope you can help me with this,
Thank you in advance.
nazareth