emacs image question

[Kada Situ]

Hi,
I am using tabbar and trying to modify it's look & feel.
Here is the code copy&paste straight from tabbar.el (2.0), it's also available here:
http://emhacks.cvs.sourceforge.net/*checkout*/emhacks/emhacks/tabbar.el?revision=1.69

(defconst tabbar-home-button-enabled-image
  '((:type pbm :data "\
P2 13 13 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 0

6 0 255 255 255 255 255 255 255 255 255 255 9 130 9 255 255 255 255
255 255 255 255 255 255 26 130 26 255 255 255 255 255 255 255 0 9 26
41 130 41 26 9 0 255 255 255 255 5 145 140 135 130 125 120 115 5 255
255 255 255 0 9 26 41 130 41 26 9 0 255 255 255 255 255 255 255 26 130

26 255 255 255 255 255 255 255 255 255 255 9 130 9 255 255 255 255 255
255 255 255 255 255 0 6 0 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255

"))
  "Default image for the enabled home button.")

(defconst tabbar-home-button-disabled-image
  '((:type pbm :data "\
P2 13 13 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255

255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 0 0 1 2 3 2 1 0 0 255 255 255 255 0 132 128 123 119 114 110

106 0 255 255 255 255 0 0 1 2 3 2 1 0 0 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255

255 255 255 255 255 255 255 255 255
"))
  "Default image for the disabled home button.")

(defconst tabbar-scroll-left-button-enabled-image
  '((:type pbm :data "\
P2 13 13 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255

255 255 255 255 255 255 255 255 128 16 48 255 255 255 255 255 255 255
255 144 28 86 128 0 255 255 255 255 255 255 160 44 92 159 135 113 0
255 255 255 255 160 44 97 165 144 129 120 117 0 255 255 176 44 98 175
174 146 127 126 127 128 0 255 255 0 160 184 156 143 136 134 135 137

138 0 255 255 176 32 67 144 146 144 145 146 148 149 0 255 255 255 255
160 42 75 140 154 158 159 160 0 255 255 255 255 255 255 160 40 74 154
170 171 0 255 255 255 255 255 255 255 255 160 41 82 163 0 255 255 255
255 255 255 255 255 255 255 160 32 48 255 255 255 255 255 255 255 255

255 255 255 255 255 255
"))
  "Default image for the enabled scroll left button.
A disabled button image will be automatically build from it.")

(defconst tabbar-scroll-right-button-enabled-image

  '((:type pbm :data "\
P2 13 13 255 255 255 255 255 255 255 255 255 255 255 255 255 255 255
48 32 160 255 255 255 255 255 255 255 255 255 255 44 161 71 32 160 255
255 255 255 255 255 255 255 36 157 163 145 62 32 160 255 255 255 255

255 255 30 128 133 137 142 124 50 32 160 255 255 255 255 29 120 121
124 126 126 124 105 42 32 176 255 255 31 126 127 128 128 128 128 126
124 89 32 255 255 33 134 135 136 137 137 138 119 49 32 176 255 255 34
143 144 145 146 128 54 32 160 255 255 255 255 36 152 153 134 57 32 160

255 255 255 255 255 255 38 141 60 32 160 255 255 255 255 255 255 255
255 48 32 160 255 255 255 255 255 255 255 255 255 255 255 255 255 255
255 255 255 255 255 255 255 255
"))
  "Default image for the enabled scroll right button.

A disabled button image will be automatically build from it.")


All I want to do is to replace the pbm data with a png image. So, I change them to the following:

(setq tabbar-home-button-enabled-image
  '((:type png :file "home_sm.png")))

(setq tabbar-home-button-disabled-image
  '((:type png :file "home_sm.png")))

(setq tabbar-scroll-left-button-enabled-image
  '((:type png :file "back_sm.png")))

(setq tabbar-scroll-right-button-enabled-image
  '((:type png :file "forward_sm.png")))

I just use the above code from tabbar-init.el which can be found here:
http://old.nabble.com/tabbar-update-p13490462.html
The image files are located in my emacs load path, the same as tabbar.el is in.
The strange this is this piece of code works under nqmacs, but no longer works after I switch to emacs. The version I am using is 23.1.1.
Any helps or advices would be appreciated.
Thanks!
-- 
___
K.S