Regex problem with a #

[Rubble]

I have written a simple regular expression to check input but have a problem with the # I have a feeling that I have another problem in that I need to limit the amount of letters in the hex value to a maximium of 6 but am not sure how.
Here is the code can somebody let me know why the # is causing a problem and any other suggestions would be helpful.

All my good inputs get through except #ffffff and now as I have added the a-f this rgb(2a,255,255) bad input gets through as well. I could always do extra tests after this one to check that only an input starting with a # has letters.

<?php
/*
Possible good inputs
rgb(255,255,255) - OK
rgba(255,255,255,1.0) - OK
rgb(100%,100%,100%) - OK 
#ffffff - No
hsl(0,0,255)  - OK
hsl(0%,0%,100%)  - OK
hsb(0,0,255)  - OK
hsb(0%,0%,100%)  - OK
cmyk(0,0,0,0)  - OK
cmyk(0%,0%,0%,0%) - OK

Possible bad inputs
rgb(2a,255,255) - Yes
rgbd(2,255,255) - No
(2,255,255) - No
2,255,255 - No
*/

//$color = $_GET['color'];

// Hardcoaded for testing
$color = "rgb(2a,255,255)";

// Change all the text to lowercase this will reduce the amount of options
$color = strtolower( $color );

// Check for valid input
// Returns 1 if a match is found and 0 otherwise
if( preg_match ( "/^(rgb|rgba|hsl|hsb|cmyk|gray)\([a-f0-9\.,%#]+\)/", $color, $match)){
echo "Wahoo";
}
else echo "Blah";
?>

[Rubble]

Of course it wont match it does not have any () in it and does not start with a rgb or rgba or hsl or hsb or cmyk or gray

Nothing at all to do with the #

Wife really impressed that I have got out of bed to post on a forum !!!!!!