PNG file won't open in CS4

[LBK_FL]

I'm trying to open a PNG file in P-Shop CS4. I do have the png plug-in, but I keep getting an error message saying

Could not complete your request because the file-format module can not parse the file.

Any suggestions?

PS I'm a newbie. Just joined today, so if this is the wrong question for this forum, lemme know what the correct one is and I'll repost it there.

[cpjr]

It should open no problem. Unless your trying to open a .png directly from the iphone....as they are encrypted by apple and cant be modified.

[LBK_FL]

That's what I was doing. Thanks.