Self-compiled PHP cannot generate PNG images under Linux, how to resolve

Self-compiled PHP cannot generate PNG images under Linux
Environment:
CentOS 6.4 64-bit
Nginx 1.4.2
PHP 5.4.7
GD library information is as follows:
GD supportenabled
GD versionbundled (2.0.34 compatible)
FreeType supportenabled
FreeType Linkagewith FreeType
FreeType Version2.3.11
GIF Read supportenabled
GIF Create supportenabled
JPEG supportenabled
Libjpeg version6b
PNG supportenabled
LibPNG Version1.2.49
WBMP supportenabled
XPM supportenabled
XBM supportenabled

Directivelocal Valuemaster Value
Gd.jpeg_ignore_warning 0 0


Now this is the case, I have a need to generate a verification code page, the use of someone else to write a code to generate codes, this code on my computer run well, on the server will appear without output image data, image handle is by Imagecreatetruecolorfunction generation, I use Var_dump to print this crank to display this information: resource (in) of type (GD)
It is clear that the handle was created, and then the generated code called these graphical functions:
Imagecolorallocate
Imagefilledrectangle
Imagettftext
Imageline
Last use
header (' content-type:image/png ')
With
imagepngfunction input Verification Code image

Finally, I found through the browser side of the debugger, although the image/png type, but there is no valid data, that is, the successful invocation of the ImagecreatetruecolorAfter the image handle has been generated, the remaining graphics functions do not write any graphics data to the image.

Now the problem is that I have to have the ability to generate verification code, including the Discuz forum to be built later will have a verification code, what can I do to make this thing work.
Since GD lacked freetype support I have recompiled PHP. I now seem to be only 1). Find out why the write graph input failed and then resolve it. 2). Re-engage another version of PHP to compile.
Would you please tell me how to do it?
------Solution--------------------
Post your code to verify that your program is writing without problems
If you are looking for a problem in a number of factors to determine, you should first use the exclusion method
------Solution--------------------
Path, Case ...

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