[imp] Can't send mail from IMP

[Mohamad Rezwan]

My configuration as follow:

Solaris 8, php-4.2.3, horde-2.1, IMP 3.0.

Every thing else works fine except when I tried to send emails...

I get the following error : 

Notice: Undefined index: params in
/export/home/source/horde-2.1/imp/lib/IMP.php on line 1018

Notice: Array to string conversion in
/export/home/local/lib/php/Mail.php on line 45

Fatal error: Call to undefined function: send() in
/export/home/source/horde-2.1/imp/compose.php on line 805

Can anyone help me pleasseeee...i'm desperate

TQ.

Rezwan