Converting Lockscreen wallpaper question

[you silly GOOSE]

I did some searching around but didn't get any good answer pertaining to my issue:

I was aiming to replace a LockBackground.png of a lockscreen theme with the wallpaper of my choice. Hence, I opened photoshop to convert the .jpg to a .png and saved it as "LockBackground.png" with the same dimensions as the original (640x960).

When i replace the undesired .png with the new one and respring my phone, the new wallpaper isn't showing up properly. It's enlarged, and hence only the top right corner of the image is shown.

To my knowledge i didn't change anything besides the file format. So, what's wrong?

Thanks in advance.

 

[you silly GOOSE]

bump

 

[ZmyDust]

Is your theme your using along with this using some type of .HTML file (for a widget of some sort on the springboard) that requires the background to be a certain size? What is the size of the default wallpaper that came with the theme and does it fit the screen properly?