a song of ice and fire - How is the murder attempt consistent with Varys' plan?

This question is about a book 1/season 1 event, regarding enlightening from book 5. The event of the book 1 will not be in spoiler tags as it happens fairly early, but the reveals from book 5 will.

In book 1, following an order from King Robert, Varys sends a poisoner to sell some poisoned wine to Daenerys.

Jorah Mormont, who by then has fallen in love with Daenerys (come on, this is so obvious that it's not a spoiler..), saves her by spotting the seller's suspicious behavior.

In book 5, it is revealed that

Varys is working in secret with Illyrio Mopatis for years in favor of the Targaryens.

I put it in spoiler tag but it can be deduced as early as book 1, during the "Arya chasing the cat into the castle's underground" chapter.

What is really confirmed in book 5 is that

Mormont was a spy for the council. He betrayed it when he felt in love with Daenerys.

Since Varys could not have possibly known that Jorah Mormont would save the day, why did he actually send the poisoner instead of just saying to King Robert "I sent him, but he failed" ?

Am I missing something ? Let me kknow if the question is unclear.

Answer

The letter that Jorah received from Varys contained a warning about assassination attempts. Varys did not send the poisoner, the poisoner acted on his own accord. Littlefinger tells Ned that he "saved" Dany by making the council agree to bestow a lordship on whoever killed Dany, rather than hire a professional (such as a faceless man).

[Littlefinger to Ned:] "After you stormed out, it was left to me to convince them not to hire the Faceless Men," he continued blithely. "Instead Varys will quietly let it be known that we'll make a lord of whoever does in the Targaryen girl."

Ned was disgusted. "So now we grant titles to assassins."

Littlefinger shrugged. "Titles are cheap. The Faceless Men are expensive. If truth be told, I did the Targaryen girl more good than you with all your talk of honor. Let some sellsword drunk on visions of lordship try to kill her. Likely he'll make a botch of it, and afterward the Dothraki will be on their guard. If we'd sent a Faceless Man after her, she'd be as good as buried."

CL4PTR4P makes a good point in the comments that Robert does withdraw the assassination order on his death bed, and that might be where the warning to Jorah comes from. Varys was (probably) the one to send the messages about the assassination, but I do not believe he had much choice in the matter: He must be seen to try, or it would cost his life.

I agree though that Varys and Illyrio's behaviour towards Dany and Viserys have been somewhat strange. Especially... (Major spoiler ADWD):

..considering the way that they have nurtured, pampered and protected Aegon for years. In contrast, they have let Viserys die, sold Daenerys to the dothraki and more or less abandoned her to live or die.

Because it is clear that they intend for Aegon to rule, considering Varys' speech to Kevan Lannister, it is very strange that they allowed Dany and Viserys to believe that they were the royal heirs. It would be very awkward if they presented Aegon to Viserys... "So... ehm... here's the real king of Westeros. Would you kindly step aside?"

I am starting to wonder about Bloodraven's involvement, especially considering that he more or less had the same job as Varys in his days. Its been speculated that Varys is a hidden Targaryen, and he does have a shaved head, much like Egg (Aegon V) in the Dunk & Egg novels.